For reproduce, install an app like seafile or nextcloud (any app which is NOT activating the online keyboard).
in seafile for example, if you try to add something in 'Server' field you have to activate the keyboard by your on with pushing the button on right bottom side. Than try any letter or the backspace key. you will see, that most keys aren't working and the backspace is adding the =.
I have made a video where you can see what happens https://ecloud.global/s/7SGd78cQ3Q8nsRt
in seafile for example, if you try to add something in 'Server' field you have to activate the keyboard by your on with pushing the button on right bottom side. Than try any letter or the backspace key. you will see, that most keys aren't working and the backspace is adding the =.
I have made a video where you can see what happens https://ecloud.global/s/7SGd78cQ3Q8nsRt