Hi, I finally found what seems to be the solution for me, and just wanted to give another update on this in case someone runs into the same problem. So, after digging some more and trying different settings, I realised what the problem is and how to solve it. It is nothing to do with my specific device (apart from that it might be an issue with Android devices in general).
So, here is the explanation:
With text input boxes, another problem that keep repeating itself (in forum discussions) it that the keyboard squashes the screen (on Android at least, as far as I am aware). The recommendation that I often see in the forums is to make the screen scrollable and the heights of the elements absolute. Now here is the thing: I avoided this advice, because I did not care much about the squashing of the screen, and most of my elements on the app use relative sizes, so I just kept it to be consistent with other screens.
Now, it turns out that this problem is related to the issue that I raised above, that is that the keyboard then also does not go away when tapping anywhere else on the screen.
Long story short, I resorted to use scrollable screen and absolute heights of elements on the screen, and the keyboard is finally completely well-behaved on both aspects of not squashing the screen AND moving away when tapping outside of the input text box.
Thanks anyway for all the support and for the great platform.