I can't work out whether this is a Chrome problem, or a Mumsnet one, but it didn't seem to be that obvious on other sites, so it may be something you've changed?
Over the last few days, I've been having real trouble with Android Chrome over-enthusiastically refreshing the page when I'm just trying to scroll back up. This is especially annoying when I'm posting a reply in a forum and I want to look back at previous posts, then the page refreshes and I lose my draft! Is this a change your end?