Same here.

With the absolute lack of details, I can only conjecture. Maybe your browser is Chromium-based, or you're using uBlock instead of uBlock Origin, or you have viruses, or you disabled it without noticing, or you managed to whitelist every domain (is that even possible though), etc.

sometimes I have to manually update my filter lists, but also ensure you're using ublock origin (as already stated in a previous reply itt)

If you're using browser to use youtube, you can try invidious, an alternative frontend.

redirect.invidious.io

I switched to uBlock Origin Lite since around that time and it has been blocking youtube ads just fine.

I had to reinstall my browser, some settings were bugging it our after youtube updated something