New (non-amazon) cover distorting writing accuracy

I bought a new cover, after the original one started fraying.

Now, when I’m writing, on certain areas of the screen the accuracy is off by a good 5 mm.

I know that the new cover is causing this - it goes away immediately I remove it from the cover. It’s one of the covers that you snap the ereader into a solid frame. When I put it back in, the problem is back! Therefore I have to send the cover back, sadly, as I like it apart from this.

I had an anxiety dream about it last night, in which the screen shattered, so I’ll be initiating sending it back today. :D

Has anyone else had anything like this happen? Back to the original amazon cover for me.