For me, it looks a bug, but not bug on Appsheet, but Discourse, which is a platform for this community place.
When we place new post, thread and comment to add, slide will pop up from the bottom. Then we are able to change the height. When we have nav bar
stays on screen, then increase the height, the nav bar menu “should” be hidden behind, but it come on the very top always, which interupt typing and playing when I type the comment for thread.
Not sure this GIF explain this bug (a but for me at least).
Z-index for nav bar should be set to lower number, I suppose.