So, does this 'official' photo mean that the transfer is now officially official, or just official? It is not on the Official web site yet (at least, not on the 'front page'), so are there further officialities required before it is officially official?
I'd imagine that the player wanted a shorter deal for that reason. We're starting to see more of that with youngsters, because it gives players an out should they find themselves without playing time (or, conversely, find themselves excelling such that they want to maximize leverage). As a team, it's a tricky choice: either you significantly enhance their wages to get them to agree to a longer deal, or you potentially lose out as they approach the end of their contract. For a spell, we did the former, and got stuck with a lot of long-term money we couldn't shift. Of late, we've done the latter, and have been forced into difficult decisions with players who had all the leverage. There really isn't a right answer there, just a question of which type of peril you'd prefer.
Man Utd seem to be adding ‘with the option for a further year’ into the contracts of a lot of their players. Maybe that will become more common. Potential scenario: he impresses with the u23s in 2021/22, he moves into the first team for the 22/23 season, summer 2023 he then is into the final year and may be attracting interest. As you say, tough for the club.
They also undoubtedly pay a significant premium to do so; team options are, for the player, the worst of both worlds given that they don't get the guaranteed money, nor the freedom to hit the open market earlier.
We got Bertie and Romero from Chelsea and they have both been quality players and great servants to the club. Very happy to have him with us. There is no downside to this deal.