Soo, I finally had time to do some tests in the last days and it seems that the reason I get the crashes is VS.
The system that compiled a working build used the Visual Studio 2017 14.13.26128 toolchain since I never updated after I installed it, while the other machines had a recent toolchain (Visual Studio 2017 14.15.26726).
I also updated today and the compiled game stopped working with the same crashlog.
(ue 4.20.3 was also tested on one of the “broken” machines, but it did not affect my problem)
edit: I run a build on a vm now which had the same problem, but I manually forced 14.13.26128 toolset in the BuildConfiguration now
edit2: yup, the build from the vm works, so it seems that the Visual Studio 2017 14.15.26726 toolset was the problem