I think some are being very narrow-sighted and a bit harsh on his overall time here. As a long time fan of the player, I'm as disappointed as anyone with how it has turned out as I had the highest of hopes for him, but you can't reduce his whole time at United to just the last couple of years.
It's clear to see that his decline in performance has come with his consistent injuries. He has been a shadow of himself since 2020/21 and you can see the change in his appearance/physique as much as his performances. Watch the video below and remember what he was capable of and look at the difference to today's version.
With regards to him leaving, it has been nigh on impossible for him to move on in the past few years, and it is the club's fault not his. He had a long, lucrative contract and nobody was going to pay a decent transfer fee for him and match this wages while he was constantly in and out of fitness and form. Besides, even during that time we have been so woefully low in quality and numbers at centre forward, he was still getting ample opportunities while available, so why the hell would he move?
Even this season, he had plenty of opportunities up until arguing with EtH vs Newcastle. Which is when fans started piling in once more. Anyway, the club need to get their butt in gear and sort out our striker issue which has been ongoing for nearly a decade. He should only leave this month if we have a proper replacement ready to come in.