An example would be useful to help answer your question. Perhaps you don't understand the move(s)?
Broken engine?

It's just not that powerful an engine.
- Basic/Free: 1 Computer Analysis per week - with a search depth of 8 ply (estimated at 2000 strength)
- Gold: 2 Computer Analysis per week - with a search depth of 10 ply (estimated at 2200 strength)
- Platinum: 25 Computer Analysis per week - with a search depth of 14 ply (estimated at 2500 strength)
- Diamond: 100 Computer Analysis per week - with a search depth of 14 ply (estimated at 2500 strength)
Why does the chess.com computer suggest bad moves? Or a good move but calls it bad?