The issue of accidentally losing your place in the feed is very common, and comes up here pretty frequently. I’ve posted about it and commented on multiple other posts about it. It’s super frustrating and affects me many times a day, but it doesn’t seem to phase the devs or at least is not a priority for them. They really have to change the behavior of that button, it’s getting a bit ridiculous at this point.

Isn't that button in the toolbar at the bottom? How would you get back to the feed if you went to your inbox?

Just updated the app to find the new "Are you sure you want to leave the feed? You will lose your progress." popup when using the back button while looking at the feed.

That is awesome, thanks so much! Could this popup also occur when hitting the "Posts" button?