That's odd! Just to confirm, do you see you're unsubscribed across devices? Also, could you check if you've got any 3rd party extensions installed? You can learn more about it here: https://goo.gl/SngxPd . Keep us posted.
We hear you. Please send a feedback report directly from YouTube with these steps: https://goo.gl/WdI0BK . While every individual report may not get a direct response back, we do review everything and use the details to investigate and fix issues. Thanks!