There’s only really two serious problem subclasses in Tasha’s - the Twilight and Peace clerics. Most others are perfectly solid and useable. Oh, and the entire ‘puzzle’ section sucks.
Xanathar’s unfortunately being the first big player-facing supplement tried to cover a lot of the big gaps from the PHB, but did it with mixed success. The problems that it had were underpowered option, not overpowering ones. The arcane archer, mastermind, inquisitive, banneret, whispers bard were all cool ideas but were just incredibly weak. Nothing that broke the game, but a load of missed opportunities. Oh, and the hexblade was a conceptual mistake. If they wanted to make melee warlocks viable, they should have just fixed the damn blade pact in generic rules or via new incantations rather than shoving all the fixes into one subclass.