Ofcom don't know what the Fediverse is.

They don't need to lawyer up if they have no presence in the UK. They can just send them a meme picture of a hamster.

Lemm.ee shut down for entirely unrelated reasons.

It might be hard to enforce for every instance but even if only 1% of instance admins get strongly worded letters threatening fines if they don’t follow the law, I guarantee you that many more will just decide that it’s not worth the risk, they close their instances and we end up with even fewer users than before.

Lol, Ofcom still are stuck trying to ban 4chan. You overestimate their ability.

Quite hard to enforce that given even with growth, it would be federated.

I disagree. I think upvotes/downvotes being public contribute overall to a high-trust culture. Mods absolutely can be stupid about it and ban people for single downvotes, but some people really do mass downvote entire communities and/or spin up alternative accounts purely to downvote.

dungeoncrawlers@piefed.blahaj.zone

This would depend on your level of interest for internationally acquired titles, in my honest opinion. Netflix has the largest field here.