They have no place on the board unlike Newcastle, and no direct involvement in the club. I'd certainly expect the clubs owners to use the fact that PIF has £bns of assets managed by Clearlake," to their advantage, which isn't against any rules.
Payments for the players aren't exceptional as Kante was a free agent, Ziyech is £8m, Mendy £15m and Koulibaly £25m so they aren't paying over the odds.
If Gary Neville and Chris Bryant are against it then I'm glad the club are doing it.