My iPad Air 4th Gen is not locking itself after going dark

iPad Air 4, screen goes off while using, touch the screen and it comes back on exactly where it was, not at the Lock Screen.

really weird.

battery is at 90%

since taking the case off a few mins ago it appears so far, to have stopped happening.

I’ve gently squeezed all around iPad and nothing happens, so I don’t think the case is squeezing it and causing a problem.

Will put the case on later to see if it happens again. Anyone seen this?

All the info on the web I can find seems to be about 2 things.

1) the black screen has turned the iPad off

2) when you touch the screen you’re back at the Lock Screen.

my iPad doesn’t do either, as soon as you touch it, it’s back to whatever you were doing before.or you return to the Lock Screen when you to

[Re-Titled by Moderator]