diff --git a/.github/files/generate-ci-matrix.php b/.github/files/generate-ci-matrix.php
index 1fa78d65d16d..ea62d1117708 100755
--- a/.github/files/generate-ci-matrix.php
+++ b/.github/files/generate-ci-matrix.php
@@ -61,9 +61,7 @@
 		'timeout' => 20, // 2022-01-25: 5.6 tests have started timing out at 15 minutes. Previously: Successful runs seem to take ~8 minutes for PHP 5.6 and for the 7.4 trunk run, ~5.5-6 for 7.x and 8.0.
 	);
 }
-// Uncomment this once WP trunk finally works with 8.1. Then merge into the above once WP latest does and we've cleaned up any problems in our own code.
-// phpcs:ignore Squiz.PHP.CommentedOutCode.Found, Squiz.Commenting.BlockComment.NoEmptyLineBefore
-/*
+// Merge this into the above once we decide PHP 8.1 is stable and WP latest works with 8.1.
 $matrix[] = array(
 	'name'         => 'PHP tests: PHP 8.1 WP trunk',
 	'script'       => 'test-php',
@@ -72,7 +70,6 @@
 	'timeout'      => 15,
 	'experimental' => true,
 );
-*/
 // Uncomment this once WP trunk finally works with 8.2. Then merge into the above once WP latest does and we've cleaned up any problems in our own code.
 // phpcs:ignore Squiz.PHP.CommentedOutCode.Found, Squiz.Commenting.BlockComment.NoEmptyLineBefore
 /*
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index fd045bb3ad60..10e112f9a495 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -149,6 +149,14 @@ jobs:
                 fi
               fi
 
+              if [[ "$WP_BRANCH" == 'trunk' && ( "$TEST_SCRIPT" == "test-php" || "$TEST_SCRIPT" == "test-coverage" ) ]]; then
+                VER=$(composer --format=json --working-dir="$DIR" show | jq -r '.installed[] | select( .name == "roots/wordpress" ) | .version')
+                if [[ -n "$VER" ]]; then
+                  echo 'Supposed to run tests against WordPress trunk, so upgrading roots/wordpress to dev-nightly'
+                  composer --working-dir="$DIR" require --dev roots/wordpress="dev-nightly as $VER"
+                fi
+              fi
+
               mkdir -p "artifacts/$SLUG"
               export ARTIFACTS_DIR="$GITHUB_WORKSPACE/artifacts/$SLUG"
               if [[ "$TEST_SCRIPT" == "test-coverage" ]]; then
diff --git a/projects/packages/connection/changelog/update-reenable-php-8.1-tests b/projects/packages/connection/changelog/update-reenable-php-8.1-tests
new file mode 100644
index 000000000000..01800185d44a
--- /dev/null
+++ b/projects/packages/connection/changelog/update-reenable-php-8.1-tests
@@ -0,0 +1,5 @@
+Significance: patch
+Type: fixed
+Comment: Set `REQUESTS_SILENCE_PSR0_DEPRECATIONS` when running tests for compat with WP trunk.
+
+
diff --git a/projects/packages/connection/tests/php/bootstrap.php b/projects/packages/connection/tests/php/bootstrap.php
index a7711b487e0f..7c950bc97fab 100644
--- a/projects/packages/connection/tests/php/bootstrap.php
+++ b/projects/packages/connection/tests/php/bootstrap.php
@@ -10,6 +10,10 @@
  */
 require_once __DIR__ . '/../../vendor/autoload.php';
 
+// Disable warning about deprecated request library.
+// @todo Remove this once we drop support for WordPress 6.1
+define( 'REQUESTS_SILENCE_PSR0_DEPRECATIONS', true );
+
 // Work around WordPress bug when `@runInSeparateProcess` is used.
 if ( empty( $_SERVER['SCRIPT_FILENAME'] ) ) {
 	$_SERVER['SCRIPT_FILENAME'] = __DIR__ . '/vendor/phpunit/phpunit/phpunit';