Recently, I noticed the keyboard would sometimes pop up at random times and I finally figured out reproducible steps.

Search any community from the sidebar and tap on it. Tap on a post and then tap and hold the screen, sliding it to the right. The keyboard should popup for some reason, even though there is no input field on-screen(after the post view is off-screen). This only seems to happen if the search field in the sidebar has text inputted. I was wondering why the heck the keyboard keeps popping up.