PHP default version has been updated to 8.1. To pin your version of PHP to a different version, see https://docs.pantheon.io/guides/php/php-versions.

Author: Pantheon Automation

pantheon.upstream.yml

@@ -3,7 +3,7 @@
 # Override the defaults specified here in a site-specific `pantheon.yml` file.
 # For more information see: https://pantheon.io/docs/pantheon-upstream-yml
 api_version: 1
-php_version: 7.4
+php_version: 8.1
 drush_version: 8
 
 # See https://pantheon.io/docs/pantheon-yml#specify-a-version-of-mariadb