We tested on two laptops, one with a GeForce RTX 2080 and another with a GeForce RTX 3060. They are laptops which means they may be trying to use the Intel GPU first. Yep that was it. We forced it to use the NVIDIA GPU and now it works!
Okay, then it is a problem with OPEN GL on Intel chipsets. I am really grateful, that you helped me on this. I think I have access to a gen 11 Intel notebook, there I can debug, what really is the problem.
