Just heard his resignation speech on the news. So much for calling for Moscow regime change, its his regime that's been replaced. After his resignation, many of his colleague also resigned. Whoever will replace him will have to be tougher to Putin else he'd also end up resigning.
Putin today signed a decree on the release of Boris Johnson from his post, due to the loss of confidence. According to Macron, Boris should have called Putin more often.
Seriously, this is the usual drama of a populist politician. Boris overinflated his image as a charismatic rebel jester and became too toxic even to his close party comrades.