Thanks for the hint and the solution. My question was in fact when will the bullseye packages quit the testing phase and be dropped in the stable repository
Is there any important ongoing issue explaining why Percona is not doing so at the moment ?
Percona Server for MySQL 8.0 packages for Bullseye will be available starting from 8.0.26 version, the same way as for upstream MySQL.
For example, if you check MySQL downloads page you will see that Bullseye packages are not available for 8.0.25 version, but available only starting from 8.0.26.
There is no exact release date for now, but we expect 8.0.26 to be released soon. Once it is released there will be an announcement for this.