There are many actually, more french people believe it as the days passes. Also people from UK, they read french press and immediately think this or that has happened, they don't know anything but they like to hate/blame the players, they hate Benzema and Mbappe.
There is nothing wrong with what happened in the group, these things happens often.
I have not seen Mbappe being selfish even for one moment in this entire Euro. They are blaming Mbappe because they can't really blame Benzema 100% but they are linking Mbappe's failure with Benzema's return. They are saying Mbappe is arrogant, too much ego etc and they say that Benzema's return made it worse.. But i didn't see that on the pitch, he was a good team player on the pitch.
Mbappe was part of every goal scored by France, he was very unselfish, mainly due to the presence of Benzema. He was also very unlucky in this Euro.
The only problem is that he wanted to be ahead of Griezmann for PKs and FKs. He probably doesn't mind that Benzema takes PK or plays the main role but he didn't want to be 3rd, behind Griezmann. But no one of that had any impact on the pitch.
Griezmann said he was the main PK taker in the presser, then Mbappe said there is no main PK taker, then Benzema came and took the PK vs Portugal, he didn't ask anyone he came and took it and Benz said that there was no main PK taker in the presser after the game..That made some Griezmann fans angry.
Griezmann was not great in this euro but they also say it's because of Benzema, they say that he plays in "his" zone like they don't know Benzema. "Benzema is stealing Penaltys from Griezmann" was often said. I find all this hilarious tbh.