Well, you know how urgent your need to upgrade is. S21U is a great phone altogether, but it’s starting to get a bit old. If you can save up, the base S23 with the newer chipset alone should be a great option. If you need it now, keep the S21U in mind as an option. It’s way better than the A54 and should be close in price

I’d recommend the S21U. Still a great phone, and quite budget too nowadays, you can pick one up for 350$ (base version). I got mine for 450$, the 512gb version. Idk really what’s your budget, though