monero4freedom
I think it is the default popup duration which can be changed in the settings somewhere. The minimum is just 10s.
This means you have to not click your screen for 10s for the default photo edit app to be fully accessible (especially the crop button, which is under the preview). Then it will disappears. If you click on the screen it will extend to the 10s all over again, or whatever your setting is.
Another "bug" seems to be that even if you click on edit/share. Let us say edit. Those two options are still there even if not visible anymore. They are therefore blocking the buttons under them.
This is actually good though, because it enables you to skip the 10s duration. You just click where "share" was, it will open a new popup for sharing, but you can just go back, and the preview will be gone.