The only person I know who had a drastic accent change was someone who had a stroke and after had a really strong South African accent. He was from Bradford and had no connection to South Africa.
i haven’t seen the video but seeing the stuff on here and social media, I really hope he’s okay and gets help if he needs it.
to add: just watched video, I get why people are saying he sounds Dutch, but to the Dutch ear deffo more French Belgium but not that strong, I do still hear his accent coming through though. Has he had any health scares? I know he’s meant to be sober.