He will probably turn up next year after a decent pre-season and look closer to his peak level. I don't think it is just attitude or commitment in his preparation(though no doubt there should be some focus there) but he has also had a couple of injury hit seasons and covid so his physical level is not where it needs to be.
Big guys like him to tend to recover slower and maybe drop off a little earlier, it is hard work carrying all that mass around the pitch, we saw it with Matic, Fellaini to an extent, could even say Yaya Toure dropped from being the best in the league to struggling to play in a 2 quite quickly. Vieria was pretty much done at his top level at 29, Ballack was never the same player at Chelsea at 30.
The club should be considering that when thinking about making him the highest paid player in the league. What is going to change with Pogba in his 7th season in his second spell?