The idea behind FFP controls is not a bad thing.
The problem with La Liga's/Tebas idea is it's far to restrictive in it's current form. It's forcing a lot of teams here in the league to sell off their prized, talented assets for peanuts, which is hollowing out the league and making it weaker making it harder and harder for the team to reinvest into the team.
Almost feels pointless in having a release clause at this point now. No point in setting one at 20-30+ when teams in the EPL can just wait it out and force teams to sell far below it due to registration issues.