On my Android phone, switching away from Liftoff to another app usually causes it to unload. So, when I switch back, it loses the scrolling position I had left, which means I have to start again at the top. Other apps on my phone don't do this, and apps used before Liftoff don't get unloaded, so I don't think this is a memory usage issue.
I'm not entirely sure whether this is caused by the same problem, but even after following a link in the comments, I often return to the top of the default page (in my case feddit.de./subscribed/hot) instead of the comment section of the post or at least the previously chosen configuration (for example feddit.de/all/active) and position.
Ive have not had this issue with liftoff but I had that issue with boost for reddit. I had change some setting or permissions for it and that fixed it. Sadly I ca t remember what those were