diff --git a/admin/class-tmdo-admin.php b/admin/class-tmdo-admin.php
index 9f11387..e4fbc65 100644
--- a/admin/class-tmdo-admin.php
+++ b/admin/class-tmdo-admin.php
@@ -3490,7 +3490,7 @@ wpdo.getListings({ per_page: 3 }).then(r => console.log(r));'
 
 			<?php
 			// v2.12.1: Term + Comment garbage write-time filter toggle + status.
-			$tcg_enabled   = (bool) get_option( 'wpdo_term_comment_garbage_filter_enabled', '1' );
+			$tcg_enabled   = (bool) get_option( 'wpdo_term_comment_garbage_filter_enabled', '0' );
 			$tcg_drops_24h = class_exists( 'TMDO_Term_Comment_Garbage_Filter' )
 				? TMDO_Term_Comment_Garbage_Filter::get_drop_count_24h()
 				: 0;
@@ -3653,7 +3653,7 @@ wpdo.getListings({ per_page: 3 }).then(r => console.log(r));'
 
 			<?php
 			// v2.12.4: Term + Comment misc bucket toggle + status.
-			$misc_enabled      = (bool) get_option( 'wpdo_term_comment_misc_bucket_enabled', '1' );
+			$misc_enabled      = (bool) get_option( 'wpdo_term_comment_misc_bucket_enabled', '0' );
 			$term_misc_rows    = class_exists( 'TMDO_Term_Comment_Misc_Bucket' )
 				? TMDO_Term_Comment_Misc_Bucket::count_rows( 'term' )
 				: 0;
diff --git a/includes/class-tmdo-installer.php b/includes/class-tmdo-installer.php
index b2c9c89..5e90c9c 100644
--- a/includes/class-tmdo-installer.php
+++ b/includes/class-tmdo-installer.php
@@ -40,6 +40,9 @@ class TMDO_Installer {
 	 */
 	private const SCHEMA_VERSION = '2.1.0';
 
+	/** Set once maybe_preserve_misc_bucket_default() has run for this site. */
+	public const MISC_BUCKET_DEFAULT_FLAG = 'wpdo_misc_bucket_default_v2';
+
 	/** Allowed SQL base types for hot-zone column definitions. */
 	private const ALLOWED_COL_BASE_TYPES = array(
 		'bigint',
@@ -299,6 +302,34 @@ class TMDO_Installer {
 		if ( get_option( 'wpdo_db_version' ) !== self::SCHEMA_VERSION ) {
 			self::install();
 		}
+		self::maybe_preserve_misc_bucket_default();
+	}
+
+	/**
+	 * One-time migration for the misc bucket default flip (on → off).
+	 *
+	 * The bucket used to default to enabled; its rows are only readable while it
+	 * is on. Sites that already hold misc rows and never set the toggle get '1'
+	 * persisted so turning the default off cannot hide their data. Runs from
+	 * maybe_upgrade() rather than install() because install() only runs when
+	 * SCHEMA_VERSION changes; the flag is autoloaded since it is read per request.
+	 *
+	 * @return void
+	 */
+	public static function maybe_preserve_misc_bucket_default(): void {
+		if ( get_option( self::MISC_BUCKET_DEFAULT_FLAG ) || ! class_exists( 'TMDO_Term_Comment_Misc_Bucket' ) ) {
+			return;
+		}
+
+		$unset    = false === get_option( TMDO_Term_Comment_Misc_Bucket::OPT_ENABLED );
+		$has_rows = TMDO_Term_Comment_Misc_Bucket::count_rows( 'term' ) > 0
+			|| TMDO_Term_Comment_Misc_Bucket::count_rows( 'comment' ) > 0;
+
+		if ( $unset && $has_rows ) {
+			update_option( TMDO_Term_Comment_Misc_Bucket::OPT_ENABLED, '1', false );
+		}
+
+		update_option( self::MISC_BUCKET_DEFAULT_FLAG, '1', true );
 	}
 
 	// ── v2.0.0 entity + audit + shadow_diffs schema (PR-2) ─────────────────
diff --git a/includes/integrations/class-tmdo-term-comment-garbage-filter.php b/includes/integrations/class-tmdo-term-comment-garbage-filter.php
index 75b2b52..1056a68 100644
--- a/includes/integrations/class-tmdo-term-comment-garbage-filter.php
+++ b/includes/integrations/class-tmdo-term-comment-garbage-filter.php
@@ -109,12 +109,12 @@ final class TMDO_Term_Comment_Garbage_Filter {
 	}
 
 	/**
-	 * Check the admin toggle. Defaults to enabled.
+	 * Check the admin toggle. Defaults to disabled.
 	 *
 	 * @return bool
 	 */
 	public static function is_enabled(): bool {
-		return (bool) get_option( self::OPT_ENABLED, '1' );
+		return (bool) get_option( self::OPT_ENABLED, '0' );
 	}
 
 	/**
diff --git a/includes/integrations/class-tmdo-term-comment-misc-bucket.php b/includes/integrations/class-tmdo-term-comment-misc-bucket.php
index 7bc52bb..80c5a55 100644
--- a/includes/integrations/class-tmdo-term-comment-misc-bucket.php
+++ b/includes/integrations/class-tmdo-term-comment-misc-bucket.php
@@ -95,12 +95,13 @@ final class TMDO_Term_Comment_Misc_Bucket {
 	}
 
 	/**
-	 * Check the admin toggle. Defaults to enabled.
+	 * Check the admin toggle. Defaults to disabled; sites that already hold misc
+	 * rows keep it on via TMDO_Installer::maybe_preserve_misc_bucket_default().
 	 *
 	 * @return bool
 	 */
 	public static function is_enabled(): bool {
-		return (bool) get_option( self::OPT_ENABLED, '1' );
+		return (bool) get_option( self::OPT_ENABLED, '0' );
 	}
 
 	/**
diff --git a/tests/integration/TermCommentGarbageFilterTest.php b/tests/integration/TermCommentGarbageFilterTest.php
index 36a69b0..2fd5d21 100644
--- a/tests/integration/TermCommentGarbageFilterTest.php
+++ b/tests/integration/TermCommentGarbageFilterTest.php
@@ -152,9 +152,9 @@ class TermCommentGarbageFilterTest extends TestCase {
 
 	// ── is_enabled toggle ───────────────────────────────────────────────────
 
-	public function test_is_enabled_defaults_true(): void {
+	public function test_is_enabled_defaults_false(): void {
 		delete_option( WPDO_Term_Comment_Garbage_Filter::OPT_ENABLED );
-		$this->assertTrue( WPDO_Term_Comment_Garbage_Filter::is_enabled() );
+		$this->assertFalse( WPDO_Term_Comment_Garbage_Filter::is_enabled() );
 	}
 
 	public function test_is_enabled_respects_zero_value(): void {
diff --git a/tests/integration/TermCommentMiscBucketTest.php b/tests/integration/TermCommentMiscBucketTest.php
index 2bca15c..28b0c31 100644
--- a/tests/integration/TermCommentMiscBucketTest.php
+++ b/tests/integration/TermCommentMiscBucketTest.php
@@ -189,11 +189,59 @@ class TermCommentMiscBucketTest extends TestCase {
 
 	// ── is_enabled toggle ───────────────────────────────────────────────────
 
-	public function test_is_enabled_defaults_true(): void {
+	public function test_is_enabled_defaults_false(): void {
 		delete_option( WPDO_Term_Comment_Misc_Bucket::OPT_ENABLED );
+		$this->assertFalse( WPDO_Term_Comment_Misc_Bucket::is_enabled() );
+	}
+
+	// ── one-time default migration for sites that already use the bucket ─────
+
+	public function test_preserve_default_keeps_bucket_on_when_misc_has_rows(): void {
+		$this->reset_preserve_state();
+		WPDO_Term_Comment_Misc_Bucket::on_term_update( null, 1, 'a', 'x', '' );
+
+		TMDO_Installer::maybe_preserve_misc_bucket_default();
+
+		$this->assertSame( '1', get_option( WPDO_Term_Comment_Misc_Bucket::OPT_ENABLED ) );
 		$this->assertTrue( WPDO_Term_Comment_Misc_Bucket::is_enabled() );
 	}
 
+	public function test_preserve_default_leaves_bucket_off_when_misc_empty(): void {
+		$this->reset_preserve_state();
+
+		TMDO_Installer::maybe_preserve_misc_bucket_default();
+
+		$this->assertFalse( get_option( WPDO_Term_Comment_Misc_Bucket::OPT_ENABLED ) );
+		$this->assertFalse( WPDO_Term_Comment_Misc_Bucket::is_enabled() );
+		$this->assertNotEmpty( get_option( TMDO_Installer::MISC_BUCKET_DEFAULT_FLAG ) );
+	}
+
+	public function test_preserve_default_respects_explicit_off(): void {
+		$this->reset_preserve_state();
+		update_option( WPDO_Term_Comment_Misc_Bucket::OPT_ENABLED, '0' );
+		WPDO_Term_Comment_Misc_Bucket::on_term_update( null, 1, 'a', 'x', '' );
+
+		TMDO_Installer::maybe_preserve_misc_bucket_default();
+
+		$this->assertSame( '0', get_option( WPDO_Term_Comment_Misc_Bucket::OPT_ENABLED ) );
+		delete_option( WPDO_Term_Comment_Misc_Bucket::OPT_ENABLED );
+	}
+
+	public function test_preserve_default_runs_only_once(): void {
+		$this->reset_preserve_state();
+		TMDO_Installer::maybe_preserve_misc_bucket_default(); // Empty tables: stays off, flag set.
+		WPDO_Term_Comment_Misc_Bucket::on_term_update( null, 1, 'a', 'x', '' );
+
+		TMDO_Installer::maybe_preserve_misc_bucket_default();
+
+		$this->assertFalse( get_option( WPDO_Term_Comment_Misc_Bucket::OPT_ENABLED ) );
+	}
+
+	private function reset_preserve_state(): void {
+		delete_option( WPDO_Term_Comment_Misc_Bucket::OPT_ENABLED );
+		delete_option( TMDO_Installer::MISC_BUCKET_DEFAULT_FLAG );
+	}
+
 	public function test_is_enabled_respects_zero_value(): void {
 		update_option( WPDO_Term_Comment_Misc_Bucket::OPT_ENABLED, '0' );
 		$this->assertFalse( WPDO_Term_Comment_Misc_Bucket::is_enabled() );