Same thing here. I've been declining the upgrade for months/years now, did it again this week. Just now I boot up my computer, get greeted by a screen telling me it will download Windows 11 in the background. Still saw the Upgrade now / Stay on Windows 10 links on the Update page (ofcourse clicked again on Stay on Windows 10, but to no avail, it was already downloading).
Killed the entire windows update process to get it to stop downloading, but no doubt it will start again soon. Why is Windows such hot garbage nowadays... I do already work with Linux and OSX, and I never had an issue like this with those.
Nevermind me having to repeat that I want to stay on Windows 10 forever, I can deal with that. But then after that still ignoring me telling it not to and just installing anway...
Get your act together.