The corrupt oligopolists have completely given up on QA; why would they bother when they don't feel any real competitive pressure.

AFAIK, this has been happening as far back as Windows 8. I believe they had a giant pool of physical PCs (laptops, pre-builts and various popular component combinations for desktop) that they physically tested updates on, but they scrapped all of it because they know they don't need to worry about competition.