The date resets when it performs a major "feature" update because the major update process technically performs a reinstall with your data excluded. The fact they can't work out how to keep the install date as well is... deeply funny to me.
One day I will burn down Microsoft over shit like this lol
As someone who regularly uses Linux alongside Windows, I've not had any issues with Windows 11 even on the dev track... Well not since I make Windows chainsaw™ that rips out shit like telemetry, recall and Co-pilot