I think any team out of the group stage in cup competitions get 0 restrictions on minutes for that competition, and also it shouldn’t be a full season cap I would probably break it up into 2 halves or maybe even quarters like 900 minutes per 12 games for example

Yeah there is a chance that would be the case.

I think it would prevent big 250k contracts and a more level wage structure which isn't a massive issue imo, but could mean big teams abroad could offer contracts if it's only a rule in England

Maybe allocate more minutes for teams in comps, or limited to just the league rather than cup comps too.

What are some negatives about a cap on minutes per player even if it's just in domestic football?

Reasons why I think it would be a good idea:
-Player fitness

-Young players and squad players get more game time which is a positive for them (especially for a Bissouma/Conte situation)

-Big teams will rotate more often leading to more opportunities for smaller clubs to cause an upset

There's probably some downsides I can't think of ????