Interest groups are open — and clans are now invite-only
Follow as many interest groups as you like to show what you're into; clans became something you're invited to.
Clans and groups are now two different things, on purpose. Groups are interests: follow as many as you like — Speedrunners, Casual Fridays, whatever fits — and they show as chips on your profile. Joining and leaving is one click, and it costs nothing.
Clans became more meaningful in the same move: you can't just walk in anymore. Joining a clan happens by invite — a clan leader sends one (you'll get a notification), and you decide. Nobody is ever added to a clan without accepting it themselves.
Together they make a nice loop: your interest groups make your profile easy to find, a clan that shares your interests spots you and sends an invite, and the choice stays yours. One safety detail: players who've blocked each other simply can't invite one another — no exceptions, no leaks.