Android is not the main version of the game, and is never tested before release, we have it because RenPy allows to make builds for that as well.
This bug doesn't exist in other versions of the game, there's a scrollable menu that allows you to go back at any point, for some reason, this part of code is being ignored on Android devices, I assume it's engine/Android limitations.
Reworking the shop fully can fix the problem, but it's not a priority at the moment, as there are more important tasks to fulfill first.
I will try to think of some easy fix for 0.31, but as you play 0.27, I can say that all upcoming versions on itch.io before 0.31 would have this bug on Android.