Madrid receive half of his transfer fee, so effectively they can buy him for half price as right now his BO sits at 60m which is competitive priced in the current market for an attacker.
We have seen this story play out before.
A) he goes back to Madrid and makes no impact. Gets sold again as his level is tier 1.5/2 sides.
B) goes to Arsenal and plays great for 6 months before settling at his level.
I'd avoid Kubo personally and mark him as a missed opportunity. Let's not ignore that Xavi has gone turds up and since Raphinha injury has forgotten that it should be Raphinha starting on the right with Lamine rotating.
Not playing Joe Cancel from Wales there and then bringing on Raphinha or Lamine onto the left coz - minutes.