Keyboard hides after focusing on input

# Bug Report

## Problem
Only happens in iOS. Browser opens as requested and everything seems fine, but when a form input field is clicked, keyboard opens **and hides again** after a quick while (sometimes 5 seconds, sometimes 0.2 seconds). Hides agains means with no further interaction: no more clicks (i.e. taps), scroll or anything at all.

Same happens with spinner: you click on a spinner, that causes an option selector to open at the bottom of the screen. This behaves as the keyboard: hides by itself after a quick while.

### What is expected to happen?
After tapping on an input, the keyboard appears (1), the site scrolls to make the input in the middle (2), an input is given (3) and after focus is lost (4), the keyboard disappears (5).

In case of spinner: after tapping on a spinner, the options selector appears (1), site scrolls (2), user chooses an option (3), focus is lost (4) and options selector disappears (5).

1 and 2 happens correctly. It is possible to give an input (3) if you're quick enough. 4 and 5 happens undesired.

### What does actually happen?
When an input (or a spinner) is tapped, keyboard appears, site scrolls, after a quick moment keyboard disappears and focus is lost by the input.

## Information
Not possible to give further information. Sorry.

### Command or Code
Right now I have the following InAppBrowser parameters: 'location=no,footer=yes,clearcache=yes,cleardata=yes,clearsessioncache=yes,toolbar=yes,zoom=yes', target=_blank. But I have tried almost any combination.
usewkwebview does not work.

### Environment, Platform, Device
Happens on iOS (v.13). On Android works just fine.
I observed that, with no user interaction at all, after steps 1 and 2 (keyboard shows, site scrolls), right before the keyboard disappears again, the console shows a message that looks funny to me: CDVIonicKeyboard: updating frame.
This happens right before the problem, no matter if the problem takes 0.2 seconds or 5 seconds, it happens right before it.

### Version information
Installed platforms:
android 8.0.0
browser 6.0.0
ios 5.0.1

9.0.0 (cordova-lib@9.0.1)

## Checklist
- [X] I searched for existing GitHub issues
- [X] I updated all Cordova tooling to most recent version
- [X] I included all the necessary information above

Reproduce the issue on iOS 13 with cordova-plugin-inappbrowser 5.0.1 using the reported input and spinner interactions, while observing the CDVIonicKeyboard: updating frame message. Trace the focus and keyboard behavior around that event; done means the keyboard and option selector remain open until the user finishes and focus is lost.

Written by the indexing model from the issue text.