Well, this is really a headache. Though I learned a trick from a friend, he taught me a trick that I followed. And the trick is that I didn't connect my wallet to my smartphone all the time. When I needed it, I just connected and used it. Then I disconnected it again.
That trick really gives a headache

I read there is one other best way that can be tried but currently Samsung 2018 product users are free to use it, I don't know if other smartphones have it, i.e. activate the samsung safe folder, move the wallet application into the safe folder and hide the safe folder.
https://www.androidauthority.com/samsung-secure-folder-908758/