I guess the only fix would be changing Lemmy to also open a post as a window on top of the background like Reddit does now, then making it reopen the feed by clicking in that area.
Most PC mice now have the little side buttons that by default go forward and back in web browsers, do you have that?
I do have the side buttons, they're set to automate control and shift though. I use them pretty often, so not much chance of changing that anytime soon...
My g502 mouse would solve this problem, but it is at home. 😕
That's a UI thing. Lemmy UI does no such thing. So there's no user-fix.
You could hack it in through code injection or a contribution to the Lemmy project though, or create a feature request.
Reddit loaded a post within-page. Lemmy loads a new page for the post specifically. A back navigation would not be too much effort. Changing to a in-page load would go against Lemmy's current UI approach.