Disclaimer: I wrote this article and made this website.
There was some talk of this issue in the recent fediverse inefficiencies thread. I’m hopeful that in the future we’ll have a decentralized solution for file hosting but for now I deeply believe that users should pay for their own file hosting.
I found this https://github.com/Marie673/Torrent_Proxy
Its in chinese so idk if its whats needed but if each instance also acted as a torrent proxy then thats decentralised domain agnostic file hosting that doesnt break frontends but also allows clients to update to do resource resolution themselves while helping to serve the fediverses files as a whole.