So I was wondering if anyone knows why the game requires the latest and greatest version of macOS, but will run perfectly fine on crusty old Windows 7? I've got an old-school Mac Pro (Xeon X5680, Radeon HD 7950 3GB) that refuses to run the game in macOS 10.14 (BG3 moans about not having 10.15), yet runs it perfectly fine if I reboot into Boot Camp/Windows 10. So obviously this is not a hardware problem, but a seemingly artificial gating of the game to the "latest and greatest" version of macOS. And nothing more recent than macOS 10.14 will install on the Mac Pro.
Yes, I'm glad I can run the game at all. But this seems like a really questionable decision by someone to limit game availability.