As a football club, their fiscal year would be in parallel to their league...thus is starting in the middle of the year and ending in the middle of the year. You can also look at quarterly YoY starting with Q2 2020....everybody in world football and most companies in the world took a revenue hit. Any FFP was/is looked at over seasons, not calendar years starting and ending on 1st Jan to 31st Dec.
All the players and staff continued to get paid throughout the entire season without a main revenue stream (matchday income). How has PSG "unlocked" more budget and revenue when they didn't have matchday revenue, their domestic TV deal isn't strong enough to justify this individual club spend because none of their competitive teams are doing anything like lower league PL teams, and they're still paying amortized fees for Neymar and Mbappe (that could be slightly reduced by some sales), to that, their sponsorship deals are not amongst the highest in club football - look to the PL for that?
And this was incremental to the "free" transfer costs incurred by multiple big name players, before Messi came on.