SwitchResX 4 versions that were compatible with macOS Catalina are also compatible with BigSur
Some visual glitches may occur on these versions however, due to visual changes in BigSur.
Version 4.11 (currently in beta) is tested on BigSur and should correct these interface errors, and bring better BigSur interface support.
As far as I know, running BigSur on Intel Macs removed the functionality of disabling a display. This cannot be worked around.
On Apple Silicon Macs, this feature should work correctly (with version 4.11), maybe even better than it ever run on Intel Macs.