I've been going to a site daily that has a tracker for when One UI 3.1 is released for Galaxy phones. So far, the tracker says that only Verizon A50s got the update in the USA. I feel your pain though. I, too, have an unlocked A50 with Android 10 in the USA.
Bah, they claim the A50 update is complete, but in the USA, it isn't. Samsung shot me this illegal agreement that I had to accept or lose my phone's functionality. It says we agree not to sue Samsung in a court of law, which is illegal to force us to agree to, so the agreement is null and void as far as the law is concerned. Samsung may have no intention of updating our phones, thinking they can hide behind that "agreement".