I don't think that it is caused by hardware/software configuration error on client's side. My guess is, it's mostly server or gwent-code related. I also experienced, that GOG-Version and NonGog-Version had different saovine-code, because the mini-games were different concerning GOG/NonGOG. I had to play different because, the behaviour was different.
While I'm watching some saovine youtube videos [GOG version] and while I'm was playing the Windows Store edition, I thought, what the heck I'm seeing in these videos, cause my computer is playing total differently from the videos? That was the proof, that there must be some differences between GOG and NonGOG versions.