diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index fa1e3f209c322..e2e72fb367482 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -29,7 +29,6 @@ includes:
 	- tests/phpstan/baselines/assign.propertyType.neon
 	- tests/phpstan/baselines/binaryOp.invalid.neon
 	- tests/phpstan/baselines/booleanAnd.alwaysFalse.neon
-	- tests/phpstan/baselines/booleanAnd.alwaysTrue.neon
 	- tests/phpstan/baselines/booleanAnd.leftAlwaysTrue.neon
 	- tests/phpstan/baselines/booleanAnd.rightAlwaysTrue.neon
 	- tests/phpstan/baselines/booleanNot.alwaysFalse.neon
@@ -80,7 +79,6 @@ includes:
 	- tests/phpstan/baselines/property.phpDocType.neon
 	- tests/phpstan/baselines/property.private.neon
 	- tests/phpstan/baselines/property.protected.neon
-	- tests/phpstan/baselines/property.unusedType.neon
 	- tests/phpstan/baselines/return.empty.neon
 	- tests/phpstan/baselines/return.missing.neon
 	- tests/phpstan/baselines/return.type.neon
diff --git a/src/wp-includes/html-api/class-wp-html-tag-processor.php b/src/wp-includes/html-api/class-wp-html-tag-processor.php
index 41788ba102a67..dd99a8324b5c6 100644
--- a/src/wp-includes/html-api/class-wp-html-tag-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-tag-processor.php
@@ -1728,6 +1728,8 @@ private function skip_script_data(): bool {
 	 * @ignore
 	 *
 	 * @return bool Whether a tag was found before the end of the document.
+	 *
+	 * @phpstan-impure
 	 */
 	private function parse_next_tag(): bool {
 		$this->after_tag();
diff --git a/tests/phpstan/baselines/booleanAnd.alwaysTrue.neon b/tests/phpstan/baselines/booleanAnd.alwaysTrue.neon
deleted file mode 100644
index 52bae4992b186..0000000000000
--- a/tests/phpstan/baselines/booleanAnd.alwaysTrue.neon
+++ /dev/null
@@ -1,25 +0,0 @@
-# PHPStan baseline for the `booleanAnd.alwaysTrue` errors in WordPress core.
-#
-# https://phpstan.org/error-identifiers/booleanAnd.alwaysTrue
-#
-# Each entry is scoped to a single file and carries an exact occurrence count,
-# so that a new instance is reported as a new error rather than being absorbed
-# silently. Fixing an occurrence therefore means decrementing or removing its
-# entry here as part of the same change.
-#
-# The goal is to empty this file and delete it, along with the `includes` entry
-# for it in phpstan.neon.dist.
-#
-# Generated by `composer phpstan:baselines`. Do not edit by hand; regenerate with
-#
-#     composer phpstan:baselines -- --identifier=booleanAnd.alwaysTrue
-#
-# which reruns the analysis with this file suppressed so the errors surface again.
-
-parameters:
-	ignoreErrors:
-		-
-			message: '#^Result of && is always true\.$#'
-			identifier: booleanAnd.alwaysTrue
-			count: 2
-			path: ../../../src/wp-includes/html-api/class-wp-html-tag-processor.php
diff --git a/tests/phpstan/baselines/deadCode.unreachable.neon b/tests/phpstan/baselines/deadCode.unreachable.neon
index f8a2c6671a783..0bd31fe524a9a 100644
--- a/tests/phpstan/baselines/deadCode.unreachable.neon
+++ b/tests/phpstan/baselines/deadCode.unreachable.neon
@@ -288,11 +288,6 @@ parameters:
 			identifier: deadCode.unreachable
 			count: 31
 			path: ../../../src/wp-includes/html-api/class-wp-html-processor.php
-		-
-			message: '#^Unreachable statement \- code above always terminates\.$#'
-			identifier: deadCode.unreachable
-			count: 1
-			path: ../../../src/wp-includes/html-api/class-wp-html-tag-processor.php
 		-
 			message: '#^Unreachable statement \- code above always terminates\.$#'
 			identifier: deadCode.unreachable
diff --git a/tests/phpstan/baselines/identical.alwaysFalse.neon b/tests/phpstan/baselines/identical.alwaysFalse.neon
index 47e10c0e67b9a..53a42542a0410 100644
--- a/tests/phpstan/baselines/identical.alwaysFalse.neon
+++ b/tests/phpstan/baselines/identical.alwaysFalse.neon
@@ -28,11 +28,6 @@ parameters:
 			identifier: identical.alwaysFalse
 			count: 1
 			path: ../../../src/wp-includes/html-api/class-wp-html-processor.php
-		-
-			message: '#^Strict comparison using \=\=\= between ''STATE_INCOMPLETE…'' and ''STATE_READY'' will always evaluate to false\.$#'
-			identifier: identical.alwaysFalse
-			count: 1
-			path: ../../../src/wp-includes/html-api/class-wp-html-tag-processor.php
 		-
 			message: '#^Strict comparison using \=\=\= between 3000000000 and 2147483647 will always evaluate to false\.$#'
 			identifier: identical.alwaysFalse
diff --git a/tests/phpstan/baselines/method.unused.neon b/tests/phpstan/baselines/method.unused.neon
index f4314a8b42a5c..bf95fbb71715c 100644
--- a/tests/phpstan/baselines/method.unused.neon
+++ b/tests/phpstan/baselines/method.unused.neon
@@ -33,13 +33,3 @@ parameters:
 			identifier: method.unused
 			count: 1
 			path: ../../../src/wp-includes/class-wp-script-modules.php
-		-
-			message: '#^Method WP_HTML_Tag_Processor\:\:skip_rawtext\(\) is unused\.$#'
-			identifier: method.unused
-			count: 1
-			path: ../../../src/wp-includes/html-api/class-wp-html-tag-processor.php
-		-
-			message: '#^Method WP_HTML_Tag_Processor\:\:skip_script_data\(\) is unused\.$#'
-			identifier: method.unused
-			count: 1
-			path: ../../../src/wp-includes/html-api/class-wp-html-tag-processor.php
diff --git a/tests/phpstan/baselines/notIdentical.alwaysTrue.neon b/tests/phpstan/baselines/notIdentical.alwaysTrue.neon
index 631833a87c3ee..99fe5295c9d55 100644
--- a/tests/phpstan/baselines/notIdentical.alwaysTrue.neon
+++ b/tests/phpstan/baselines/notIdentical.alwaysTrue.neon
@@ -38,21 +38,6 @@ parameters:
 			identifier: notIdentical.alwaysTrue
 			count: 1
 			path: ../../../src/wp-includes/functions.php
-		-
-			message: '#^Strict comparison using \!\=\= between ''STATE_COMPLETE'' and ''STATE_READY'' will always evaluate to true\.$#'
-			identifier: notIdentical.alwaysTrue
-			count: 1
-			path: ../../../src/wp-includes/html-api/class-wp-html-tag-processor.php
-		-
-			message: '#^Strict comparison using \!\=\= between ''STATE_INCOMPLETE…'' and ''STATE_READY'' will always evaluate to true\.$#'
-			identifier: notIdentical.alwaysTrue
-			count: 1
-			path: ../../../src/wp-includes/html-api/class-wp-html-tag-processor.php
-		-
-			message: '#^Strict comparison using \!\=\= between ''STATE_MATCHED_TAG'' and ''STATE_READY'' will always evaluate to true\.$#'
-			identifier: notIdentical.alwaysTrue
-			count: 1
-			path: ../../../src/wp-includes/html-api/class-wp-html-tag-processor.php
 		-
 			message: '#^Strict comparison using \!\=\= between 0 and int\<min, \-1\>\|int\<1, max\> will always evaluate to true\.$#'
 			identifier: notIdentical.alwaysTrue
diff --git a/tests/phpstan/baselines/property.unusedType.neon b/tests/phpstan/baselines/property.unusedType.neon
deleted file mode 100644
index 9f1bd06e86c8f..0000000000000
--- a/tests/phpstan/baselines/property.unusedType.neon
+++ /dev/null
@@ -1,25 +0,0 @@
-# PHPStan baseline for the `property.unusedType` errors in WordPress core.
-#
-# https://phpstan.org/error-identifiers/property.unusedType
-#
-# Each entry is scoped to a single file and carries an exact occurrence count,
-# so that a new instance is reported as a new error rather than being absorbed
-# silently. Fixing an occurrence therefore means decrementing or removing its
-# entry here as part of the same change.
-#
-# The goal is to empty this file and delete it, along with the `includes` entry
-# for it in phpstan.neon.dist.
-#
-# Generated by `composer phpstan:baselines`. Do not edit by hand; regenerate with
-#
-#     composer phpstan:baselines -- --identifier=property.unusedType
-#
-# which reruns the analysis with this file suppressed so the errors surface again.
-
-parameters:
-	ignoreErrors:
-		-
-			message: '#^Property WP_HTML_Tag_Processor\:\:\$skip_newline_at \(int\|null\) is never assigned int so it can be removed from the property type\.$#'
-			identifier: property.unusedType
-			count: 1
-			path: ../../../src/wp-includes/html-api/class-wp-html-tag-processor.php