I'll say this as a full member of the disbanded Martial FC - something changed in 2020/21 in the change of seasons. Not sure it was injuries, but even in good form, he's never been the same player after that.
When he arrived, he was an electric dribbler, because of speed, agility, and close control. He was also a superb finisher 1v1, and could play very well as both a 9 or a left winger. His obvious weakness was movement off the ball as a striker, but that was the only thing missing. Check out his first start (Southampton away, perfect #9 performance, IMO still his best game) or the horrible away game at Arsenal (where his dribbling made him a one-man attack from the left), or the last league game vs West Ham (speed and strength).
The dribbling reduced as he bulked up once Jose arrived, even though he continued to be used as a winger. His finishing was still great (in the short spells he had as a starter in 2017/18, he scored some clinical goals). And this was clear in his best season, despite a lengthy injury in the middle of it- 23 goals and 12 assists in 2019/20, playing as the undisputed 9. Dribbling isn't what it was, but he was still sharp, great control, and ice-cold finishing.
The types of mistakes he made once the next season started went beyond bad form. It's not that he wasn't agile enough to dribble - he was now actually clumsy with the ball. That had never happened before. Bad finishing - missing sitters, hitting 1v1s to the keeper instead of chipping or placing in a corner, slipping, mis-controlling... Things that has never gone wrong were totally off. This continued next season, though he played so little it's hard to say. I remember the 9-0 Southampton game where he scored a rare goal but still looked like a donkey compared to what he used to be, it's when I gave up on truly believing in him.
Some of his core strengths seemed to come back for a while after EtH came in, the finishing was good, the play with back to goal was sharp...then he got injured, twice, and now he's a total oaf again.
Is it all injuries? I don't know, they definitely played a role. But something basic is very broken and can't be fixed, and I'm not sure it's all down to lack of effort or whatever.