a brilliant move is when your opponent made a mistake that allowed you to play a brilliant move e.g. bobby fischer's game of the century 17. Be6
Brilliant Moves in New Game Analysis Report

ok I just want to say, to get a brilliant move you have to play a move that is not necessarly the best, but that either sacrifices a piece/pawn or that is very hard to find like a random king move in an engame (there are more). You also have to be either going to lose or draw or the second best move if you're winning has a like maximum +2 advantage (-2 for black ig).
This is very close, but there are some nuances to how chess.com defines a "brilliant". The one thing I think is incorrect here is when you say "that is very hard to find", since that's going to be relative to each person. Here's the full explanation from the chess.com site itself: https://support.chess.com/article/2965-how-are-moves-classified-what-is-a-blunder-or-brilliant-and-etc#:~:text=We%20replaced%20the%20old%20Brilliant,had%20not%20found%20the%20move
There are a couple of requirements that need to be met before Game Review calls a move a brilliant:
- It needs to be a piece sacrifice. Random king moves in an endgame don't count. Unless it sacrifices a piece, I guess.
- The resulting position can't lead to a lost position. I read this as "A brilliant can win you the game, or bring it to dead even, if saving you from a loss."
- You're correct that it doesn't need to be the best move, but you're also correct that the position can't just be completely winning if the sacrifice didn't occur in the first place.
- A "piece sacrifice" can be defined differently for a lower rated player than a higher rated player. If the sacrifice is "obvious", then the higher rated player may not receive the "brilliant" move. There's no clear explanation of this particular difference.
I do have a new brilliant. This is brilliant because of the pin on the f3 knight. I was playing as black.
https://www.chess.com/analysis/game/pgn/hBeJPS1CJ?tab=review look at how bad these moves were
Brilliant move is the best move which the engine can find only after certain depth is reached. So it is difficult to find for the engine.
You are exactly right.
But if the engine finds it, it is assessed as best. It cannot be assessed as "Brilliant".
Correct me if I am wrong. Have you ever seen the engine proposes a "Brilliant" move as "Brilliant" or as "Best"? I believe NEVER.
If the engine says "Brilliant", it means "I could not find it myself"
I've actually had a brilliant move suggested to me by stockfish and it classified it as brilliant, also 9/10 times the move is a sacrifice though

ok I just want to say, to get a brilliant move you have to play a move that is not necessarly the best, but that either sacrifices a piece/pawn or that is very hard to find like a random king move in an engame (there are more). You also have to be either going to lose or draw or the second best move if you're winning has a like maximum +2 advantage (-2 for black ig).
I would bet if you run 2600+ players games thru the process you would probably find those as !! But a 900 level players !! is a far different thing. You have to give them some '!!'s ' too...
What is this supposed to mean ?

ok I just want to say, to get a brilliant move you have to play a move that is not necessarly the best, but that either sacrifices a piece/pawn or that is very hard to find like a random king move in an engame (there are more). You also have to be either going to lose or draw or the second best move if you're winning has a like maximum +2 advantage (-2 for black ig).
I would bet if you run 2600+ players games thru the process you would probably find those as !! But a 900 level players !! is a far different thing. You have to give them some '!!'s ' too...
What is this supposed to mean ?
It's simple really: The criteria for a !! (has...can't say for certain now) been different between very highly rated players and very bad players. Read back in the thread, there is a lot of discussion about it.

e... dxc4 9. xc4 O-O 10. a3 h6 11. e1 e8 12. h3 d7 13. b5 e7 14. c3
0.00 8... O-O 9. c5 b8 10. c2 b6 11. cxb6 axb6 12. e3 b7 13. ac1 b4 14. b3 c6 15. a3 a5
+0.03 8... h6 9. c5 c7 10. c2 O-O 11. a3 b6 12. b4 bxc5 13. bxc5 e8 14. d1 a6 15. h3 b7 16. e3 a5 17. d3
Réti Opening
1. d41. f3 d52. e3 e63. e2+0.033... c5+0.034. d4 f65. O-O+0.035... cxd46. exd4 c67. c4 d68. c3+0.081... c62. f3 g63. c31-0Upgrade to Save
ok I just want to say, to get a brilliant move you have to play a move that is not necessarly the best, but that either sacrifices a piece/pawn or that is very hard to find like a random king move in an engame (there are more). You also have to be either going to lose or draw or the second best move if you're winning has a like maximum +2 advantage (-2 for black ig).
I would bet if you run 2600+ players games thru the process you would probably find those as !! But a 900 level players !! is a far different thing. You have to give them some '!!'s ' too...