Microsoft is the one the TFA refers to cryptically when it says "the Faster CPython team lost its main sponsor in 2025".

AFAIK it was not driven by anything on the tech side. It was simply unlucky timing, the project getting in the middle of Microsoft's heavy handed push to cut everything. So much so that the people who were hired by MS to work on this found out they were laid off in a middle of a conference where they were giving talks on it.