Firstly, it could just as easily be that AMuS made that quote up. We didn’t see a video or anything, so we don’t know who’s lying there.
Secondly, there was no private agreement/discussion after 2021. There was a meeting where they described the changes to the stewarding.
Thirdly, if there was a secret meeting, the FIA wouldn’t let Mercedes’ cheat to “return the favour” since its not just Red Bull being impacted.
Fourthly, Max winning wasn’t a premeditated fix by the FIA. Regardless of your opinion on what happen, there was no deliberate conspiracy against Hamilton. So, there’s no favour to return.
Finally, just move on from your frankly idiotic conspiracy theories.