Up to 97 GBs in my Mastodon bucket. I have a cron job removing content older than 90 days, but I just ran it manually to make sure.
To be fair, I may not be at "equilibrium" yet, and will continue to grow until I actually hit 90 days' worth of content.
The social network of the future: No ads, no corporate surveillance, ethical design, and decentralization! Own your data with Mastodon!