you sacrificed a piece but ur move is still a good move so chess.com considers it brilliant even tho it’s not actually the best move
How are these brilliant moves?

They were each technically sacrifices
Brilliants don’t need to be tough-to-find or special, all they need to be are reasonably accurate sacrifices

I'm gonna say for the first move (move 16) it could've been because you sacrificed the g pawn to the black bishop.

Does the briliant moves depends on your ELO?
Yes, move classifications are influenced by ratings.

god i hate how this forum is being plagued by off-topic posts
I see similar questions as wondering if the classification may be a bug.

I think a move should only be considered for brilliancy if it's also the best move. Is a move really brilliant if it's unnecessary? Also maybe brilliant tags should be retroactively taken away if you don't find the follow-up.

I think a move should only be considered for brilliancy if it's also the best move. Is a move really brilliant if it's unnecessary? Also maybe brilliant tags should be retroactively taken away if you don't find the follow-up.
Just focusing on the second part of this, retroactively taking away doesn’t make sense. If they don’t find the idea then that’s that, but first off, with the “good sacrifice” definition of brilliants, a lot are easy to find
and the main reason why is that how someone plays in later moves doesn’t change how good the current move itself is. For example, if someone plays a best then finds the wrong idea, the wrong move that they played was the bad move, the best was still best.
how is capturing a PAWN that good??
I just castled?