I don’t think they did. Unless you have evidence otherwise, I think this is a rumour which comes from a misunderstanding of how deletion tools worked.
They did it to my comments. I had a like 15 year old account, hundreds of thousands of karma, and I deleted all of my comments that I could view in my profiles history and then deleted my account. Days later I found not only was my account undeleted, all of my comments that I deleted were back as if nothing ever happened - and my account was banned.
I've been saying for YEARS that the EU has been overstepping their bounds by forcing companies to do things that they should have no right to force them to do, and that the EU is becoming a threat. I was downvoted every time and called a "bootlicker" because people loved the EU dictating terms to the "big bad american corporations".
Well now the EU have gone full nanny surveilance state, and people like those who argued against me have no one to blame but themselves. Congratulations.