Either they're keylogging, which has to be done client side, or they're not. Which is it?
I linked you to the client source code. Tell me where in that source code you see a keylogger, and I will personally guarantee your name will be on the front page of this website tomorrow as uncovering what is almost certainly one of the largest keylogging networks in history.
Your "server side" handwaving is bullshit and constitutes evidence that you know nothing at all about how the technology actually works.
If AdBlock were making connections to some server to send back keylogging info, that would be headline news, but requires evidence to be taken seriously.
Right now, you cannot be taken seriously. You can only be taken as a spewer of Fear, Uncertainty and Doubt.
At the very least, one would be able to see the data (or suspicious data, if it is obfuscated) being sent from the web browser to the server in the 'Network' tab of the web browser's inspector/developer-tools. Do you see any such suspicious data being sent from the web browser to the server? Can you post a screenshot if you do?
More fundamentally, your claim is not falsifiable https://en.wikipedia.org/wiki/Falsifiability
i.e. you can't claim something true on the basis of the other person not being able to reasonably have a way of disproving it!
edit: upvoted you because you probably are on smoking something and these people are picking on you for it
N.B. At the time of this comment, the time-stamp of the above comment is 9hrs ago and the account is 13hrs old.