[charcircuit]

YouTube recommendations are only based off your activity on YouTube. Google doesn't even read your emails for ad targeting. Your anecdote was just confirmation bias.

[Operative0198]

The suggested video was too specific to be just an anecdote. YouTube doesn't need an account nor cookies to show you videos. They know you if your browser is fingerprintable enough.

I did the test on a fresh new profile.

[shadowgovt]

Almost every time, that sort of phenomenon occurs because people's consumption patterns aren't nearly as unique as they think they are.