It seems like a bug. Of course you can't force Google to remove these data internally, but if they don't want to be sued, they have to hide them from the users themselves. So it looks more like a bug from pre-GDPR times that will be removed relatively quickly. Not to mention the caching issue: if you opted out recently, the change might not be immediate.
Full disclosure: yes, it's my tweet. I reposted it not for the sake of self-promotion, but because I believe this may be important, and I am interested in more attempts to reproduce this "bug".
Regarding your comments: my history has been disabled 2 years ago, and it had been guarding me from having unrelated stuff in recommendations well enough. Few months ago I noticed that random clicks on YT links started affecting my recommendations. So it's obviously not a caching error, and it persists for noticeable time as well. Time when the issue first happened doesn't correlate with GDPR either.