Are brilliant moves actually bad in game review?
No. You don't know what exactly you mean. Brilliant moves aren't luck but depends with your tactical awareness. So... try researching and see
On chess.com "brilliant move means "a sacrifice that's good".
It can happen even if both players play perfectly. It doesn't require anyone blundering.
@Heliocrab, there is THEORETICAL LINES involving brilliants, so no, they can happen even with no mistakes.