Several problems with different keyboard layouts

I made the mistake to not enforce installation of Swiss German kbd layout from the very beginning, respectively did I enter the SSD encryption PW with a wrong kbd layout and the proposed input of '-' (dash) in the PW has become '/' (slash) due to the US-layout behind my German kbd.
Now I have to enter 'mypw/2020' instead of 'mypw-2020'.
But this is not true for all cases. As soon as I reboot the computer, the Swiss German kbd layout is retained somehow in the SSD decryption PW input too. Thus I have to enter two different PW for cold start and for warm start: mypw/2020 or mypw-2020.
But this is not all: Somehow the user PW is also influenced, funny enough with the same character, the dash.
I need to enter "mypw'2020" on my Swiss German kbd.
I haven't found what the reason for this oddity is, but anyway, somehow mixed-up kbd layouts, respectively unknown layout before unlocking the encryption or before entering the user PW.