for the millionth time, messages that are copied to other instances (so-called "federation") have their own copies of those messages, and most importantly, can do whatever they want with them.
this means they can do:
- full-text search
- rewriting your posts to say "HERP DERP"
- replacing your video/audio links with fart sounds
- replacing your images with make ________ great again memes
if you do not understand this, the federated web (Mastodon, et al) is not for you.