Per T316078, quibble tests (PHPUnit, Selenium, etc.) now need to pass on PHP 8.1 for automatic merges of changes in Gerrit.
Thanks to everyone who helped to make that happen.
PHP 8.1 support is a focus of the Wikimedia Performance Team. We
want to unblock the WMF production migration to PHP 8.1, which
will be led by Service Operations. Hopefully Service Operations
will be able to migrate WMF production to PHP 8.1 in the first
half of next year.
PHP 8.1 will bring performance improvements which we would like
our users to benefit from. And bringing production closer to the
upstream master branch allows us to more effectively participate
in PHP's community-driven development process.
For the benefit of developers and third party users, I think we
should try to support the latest stable release of PHP. So now is
a good time to start thinking about PHP 8.2 support. General
availability of PHP 8.2 is expected on around November 24,
according to the PHP wiki. There is a
migration
guide.
-- Tim Starling