The story I’ve heard is that he took a nosedive in effectiveness as CEO when his son died in 2022 (https://www.nbcnews.com/news/us-news/microsoft-ceo-satya-nadellas-son-dead-26-company-says-rcna18320). No idea how true that is, but 2022ish does seem to have been a turning point for Microsoft in terms of strategy and how well the company is run.