I know there are quite some #mastoadmin struggling with the disk space usage of the mastodon instance they maintain. The issue is not acknowledged enough and there are very few ways you can mitigate this using the official mastodon tools etc. Even better, often the proposed 'solution' is to 'get more disk space lol'.
Here's a compilation of recipes on how we try to deal with this for post.lurk.org as we learn by doing.
In general we document many parts of lurk.org on that wiki so that other collectives can use that information: