Just to provide update; I got the charge cable out.
It was, as Harleyguy stated, the release mechanism not fully enganging.
it is not the originally charge cable, so this can happen on other cables as well.
Just to inform, I managed to use a thin screw driver, a lot of light, and care to lift the locking arm on top of the connector up, so I could pull the connector out. No damage to the charge port, or the cable, so all working fine now, but I am checkin the release mechanism on the cable
Thanks again to Harleyguy, when I knew the cable is not locked to the car, as beeing the case for the charge connector on my BMW i3 and Mercedes EQ, I could apply the right «motivation» to fix this without breaking anything.