@Fry-kun Do you use auto-download? You can, as you indicated, enable Episode Cleanup (even with a delay after finishing). If you set the episode cache a bit lower, it’ll delete episodes before your phone storage is actually getting full.
Otherwise automatic cleanup should be discussed in context of https://github.com/AntennaPod/AntennaPod/milestone/47, specifically https://github.com/AntennaPod/AntennaPod/issues/5236 I think (Proposal for Auto Download Redesign might be the relevant forum post).
But regarding your original issue: doesn’t the new mechanism work for you, like @Matth78 described? Or is it the fact that the filter is not available any-more?