In a move which was announced some time ago, and as a consequence of Brexit, Meta has said that it will begin moving its UK users (Facebook, WhatsApp and Instagram) from the Irish subsidiary to the US subsidiary, i.e. outside the (EU) GDPR jurisdiction.
This means that (UK or EU) GDPR rules may be more difficult to enforce, although UK users should still be protected by the UK GDPR.
What in means in practice remains to be seen.