@vito Cleanup likely IS working, but you are probably subscribed to a ton of relays and all those relays bring in toots that you never interacted with, but Mastodon keeps the profile pics and such cached anyways.
A lot of my problems on a single user instance were fixed by moving to Akkoma. Akkoma, and Pleroma which it forked from, do not cache anything. Images are downloaded when needed only. I am now subscribed to even more relays than I was on Mastodon, but instead of having 50-100GB of images cached (on 7 days retention), my entire instance is about 4GB total. This also means that you don't run into problems where you need to reload your browser tab because Mastodon got unresponsive and Akkoma also has features like quote posts too. And it's far lighter on system resources to boot. With Akkoma, you can even use the same Mastodon user interface if you want.