Microsoft has boasted 30% of their code written by AI.[1] However we could only guess if AI generated code is the issue or something else, or a combination of things.
That being said there was a noticeable trend starting around 2022.[2] That being said they’ve also been doing a big migration to Azure. It’s likely a combination of things.
1: https://www.cnbc.com/2025/04/29/satya-nadella-says-as-much-a...