Sorry, but he's regressed. There comes a point where it has to go beyond "promising", but I've been watching the bloke for over 2 years now and he is literally no better than he's been for the last two seasons. He got those 2 goals vs Spurs on his full debut on 5th October 2019 - and then didn't score again until the final day of that season (so 3 goals in 24). Then last season, he scored a grand total of 2 goals.
I've tried to be patient, but it has become abundantly clear that he is simply not up to it at Premier League level. He is, at best, a lower-end Championship striker. I would LOVE him to prove me wrong.
But he won't.
There comes a point and that point is not when you are 21 years old. In two years I think he will be a fine PL striker, at the moment he is a decent one. I could be wrong but I dont think so.