You are just being lucky. Youtube have been rolling out new adblock filtering globally for the last few weeks.

See https://www.theverge.com/2023/10/31/23940583/youtube-ad-bloc...

This works for me too having my youtube account logged in.

Steps: click the U icon, click the gear, click filter list, click Purge, click Update.

Ads are gone again while logged in. You might have to do it again every now and then.