@mima there are multiple ways:
tbh that could be fixed within *oma since there is a mediaproxy cache blacklist as well as the option to invalidate cache via http or a bash script.
tbh i didn't have time to set any of that up correctly.
On the other hand, if you send media through fedi, then the media reached the public internet and deletion from the public internet is impossible anyway, especially for the fediverse by design of the protocol