That's literally and provably not true in this case. Maybe don't rely on generalizations? They you lead you into error.BG3 scored high early on very few reviews. Scores always come down in that situation.
If we subtract the single Eurogamer review, BG3 would still be at 97%, just like it was at the start. It is not because "scores always come down". That is provably false. It's because of one specific review which is being treated as wildly lower than the other ones.