If I use my iPad (7.1) with connected Bluetooth Keyboard I have problems with repeating keys.
If I press "space" once it is always repeating space until I disconnect the session.
I already tried your keyboard event test site
And the problem is reproducible with your test site(see screenshot, i pressed space once!)
I also tried another keyboard event test site:
And there it worked as expected(see screenshot, no repeating key presses)