Hey, this is still a valid issue on 1.17. I don’t need to do anything to reproduce it, it just doesn’t work. Like OP had said all you need to do is try to change the texture pack resolution and nothing happens. Its just defaulted to the highest resolution.
I’m trying to do this on 1.17 joining a realm. I’ve restarted my game, redownloaded my game, and still nothing.
Can you upload a screenshot?