Chess.com is more sophisticated than this in the treatment of blunders. They are divided into “misses” and “blunders”.
In my experience, it appears that the difference between the two is that a “miss” is something the computer evaluates as unreasonable or difficult for a human to find. If you had found it, it would have been deemed a “brilliant” move, which is another analysis move type that chess.com has doesn’t have. Either that or a miss is failing to capitalize on an opponent’s blunder.
It makes sense to chess players, since we consider missing an opportunity to capitalize on an opponent’s mistake to be distinct from unilaterally making one’s own position worse, even though to lichess those are going to both look like drops in the evaluation score.
Chess.com isn't really more sophisticated than lichess - it's only trying to appear so.
It's definition of blunder etc is still based only on engine evaluation. For example it marks as briliant all sound sacrifices, even the most routine ones. This is good marketing, but I doubt it's good analysis.
It's just marketing to make players feel better about themselves.
For example when i tried chess.com out they marked a simple queen sacrifice to deliver back rank-checkmate as brilliant even though it's an obvious move for any intermediate player with half a year of experience.
Lichess does nothing of that marketing bs.
In my experience, it appears that the difference between the two is that a “miss” is something the computer evaluates as unreasonable or difficult for a human to find. If you had found it, it would have been deemed a “brilliant” move, which is another analysis move type that chess.com has doesn’t have. Either that or a miss is failing to capitalize on an opponent’s blunder.
It makes sense to chess players, since we consider missing an opportunity to capitalize on an opponent’s mistake to be distinct from unilaterally making one’s own position worse, even though to lichess those are going to both look like drops in the evaluation score.