Messi is a talented and well-performing player. He didn't have a bad performance in PSG at all but since he didn't get good results because of many other reasons, the fans started attacking this player and they were thinking he is guilty of everything. That's why he could have enough focus to have better performance.
Leaving PSG this season was not something unexpected for us.
If Messi was a normal average player, then no one would complain to him - he more or less did some work and maybe no one would pay much attention to it. But Messi is supposedly GOAT and around him is always phenomenal PR and this obviously has consequences in terms of expectations from such a player. He failed all expectations, so the claims of the fans are quite obvious. When you buy a luxury car for 10x the price of a regular car, you expect a lot more performance than a regular car, right? Everything here works the same way.