There seem to be some serious issues with pulpcore 3.14, which came with the update to 2.5.2/4.1.1.
Topic on your error is here: CentOS 8.4 BaseOS Sync error
So far it seems to be an issue only with the EL8 BaseOS repositories.
With pulpcore 3.14 there is also some metadata from the RPMs missing in the database which can cause dependency errors. See topic Cannot update puppet-agent to 6.24.0 on foreman servers
At the moment I don’t install updates from katello anymore but use CentOS mirrors to update, if necessary.