@pwaring @mastohost AIUI yes. The problem is entirely large media posts and it should be entirely fixable by purging more aggressively or not even preemptively fetching to begin with.
But this requires some modifications to Mastodon I think and I'm not clear on whether mastohost gives you the capability to do that (ntm mastohost is targeted at folks who don't want to or know how to do that).
It also seems like fixing the problem is financially de-incentivized if users are having to pay for more storage to work around the problem, unless they're selling the storage at-cost.