I didn’t realise that uMatrix still saved cookies after you’ve blocked them, so now I’ve installed Cookie AutoDelete too. Thanks for the tip :)
and I still get those, sometimes even in private mode.
I use https://invidio.us/ when I want to watch something that is on youtube.
Isn’t uMatrix an advanced version of uBlock Origin? What’s the rationale behind using both of them?
(I’m the author of the linked-to blog entry.)