I've just set up a brand new PS5 controller (via Bluetooth) on Ubuntu 20.04 with kernel 5.11.0-44-generic and 'sudo evtest' seems to show it is working. It reports events for almost all the buttons.
Re-reading your bug report I think you have a problem specific to Steam. The errors you mention from Xorg (gdm-x-session[1946]: (II) ...) are probably not relevant and should be ignored. ** Changed in: linux-hwe-5.11 (Ubuntu) Status: New => Invalid ** Changed in: xorg-server (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1955932 Title: ps5 controller no longer working To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-hwe-5.11/+bug/1955932/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp