Ansu was never like Dembele gliding past defenders. He had some foot skills, which he still does, that can unmark him or give him angle for a shot from the left half-space. That's about it.
All this talk that he is physically depleted now after the injury is totally unfounded.
On the contrary, his block is 100% mental.
We see situations were pre-injury Ansu would have judged correctly and made the correct decision, and now he simply doesn't, He is too much afraid as Don Juan says
More evidence that it is completely mental, is his short spell in 21/22 under Koeman and interim coach, where he was like old Ansu whenever he played, scoring wondergoals (Celta) and another 3-4 in the few minutes he played in all coms.
The mental thing started at the beginning of 2022/23 season