Then yes the other thing is that it's using the Intel integrated graphics instead of the RX5700. Either the RX5700 doesn't have a driver set up or it's ordered or prioritized in some way different from a regular macOS install.
The way the 2 graphics cards in macOS is supposed to work is that when an app creates an OpenGL context the system is supposed to automatically use the discrete GPU instead of the Intel integrated GPU unless the app has specifically requested to allow the integrated one (which MoI does not do): https://developer.apple.com/library/archive/qa/qa1734/_index.html