speaking of Firefox, sometime within last few months it had an update where they instituted a feature where Firefox itself automatically determined what cookies came from high spam places and they were deleted without asking the user.
For several weeks it was a bit annoying to me, maybe the AI had to learn what my normal is.
Give me a moment to look and see if I can find any documentation related to that.
Okay, this may be that,
Latest Firefox rolls out Enhanced Tracking Protection 2.0; blocking redirect trackers by default - The Mozilla Blog