I’m having the same issue (for months now). Discourse pages just don’t respond on scrolling or keyboard (basically unworkable if you can only read the top of a thread). It has to do with interference with a Chrome extension probably as it doesn’t occur on other browsers or Chrome Canary (which doesn’t have any extensions). Indeed removing the <section id="splash"> element from the DOM with devtools makes it work. When I inspect in working browsers, that section element is not there upon loading, so there may be something keeping it in the DOM in my default Chrome. However I have removed my Bitwarden extension and the problem is still there (don’t have the Youtube autoquality plugin).
Any advise on how to find the culprit is welcome.
Probably not relevant but working on Mac OS.