The law is largely down to who argues better in court. There is precedent for reduced rights in public spaces. e.g. if you go into the town square and talk to someone and it’s caught on the camera of the mother a park bench away that’s recording her child … that’s not an illegal recording and she has the copyright on said recording. You have no legal right to ask the mother to delete the recording or delete your audio from the recording, even in a two party consent space because you have no right to privacy in a public setting like that.

Similarly, when you post on Lemmy … it’s kind of good faith that if you delete something it actually gets deleted from the platform across all instances and that it’s not just visibility deleted but deleted from the databases under the hood.

You do “own your content” but it’s pretty meaningless ownership.