They had a problem with him for a better part of a decade. That's why he lived in Middle East for a long time. He's basically exiled outside short, curated visits for specific dealings with pre-approved people because he stood up to Russian attempts at censoring VK and Telegram back in 2010s.
They forced him to "sell" VK to the government affiliated parties, after which he fled and kept Telegram. He's basically a post-Soviet tech bro (far less trusting of government overreach than Western tech bros). Problem is of course he's not trusting of all governments, which is why French grabbed him and are still holding him under house arrest to ensure that their superlegal backdoors remain in place.
Because he told everyone to fuck off. It's why Telegram remains so hilariously popular in nations where government suppresses peoples but hasn't gone all the way to blocking. I.e. the first one to get turned off in places like Iran through government blocking was Telegram, because the likes of Whatsapp have limited cooperation with government when it comes to things like "hate speech" which governments like Iran use to unmask and kill dissidents.
The reason why we see so many bots screaming about how he's evil, he's been got, etc, is because he's the wild card tech bro with a massive chip on his shoulder for government overreach, and who's far less amiable to both soft and hard coercion than likes of Zuckerberg and Musk have demonstrated themselves to be.