You clearly have little experience in M and A. Performance and similar clauses are not uncommon. They can cover claw backs as well as add ons
https://www.holmes-hills.co.uk/news/2022/june/a-guide-to-earn-out-provisions/
They are reportedly asking for proof of age - but how many or all I don't know
I always have a problem because I don't look my age 😁
They could contact club and see if it can be upgraded