Having the same problem. I deleted the configs in .config/wireplumber and that worked for me.
Also as a note it is probably related to that - the release notes for wireplumber 0.5 mention: https://pipewire.pages.freedesktop.org/wireplumber/resources/releases.html
The configuration system has been changed back to load files from the WirePlumber configuration directories, such as
/etc/wireplumberand$XDG_CONFIG_HOME/wireplumber, unlike in the pre-releases. This was done because issues were observed with installations that use a different prefix for pipewire and wireplumber. If you had awireplumber.conffile in/etc/pipewireor$XDG_CONFIG_HOME/pipewire, you should move it to/etc/wireplumberor$XDG_CONFIG_HOME/wireplumberrespectively (!601)