I have a similar setup and in the end just went for a cheap chinese („ESKEVE“) 4x HDMI 2.0 KVM switch that supports 4K60. No problems except HDR does not work properly, which is not useful on my monitor anyway. Laptops are on USB-C docks with HDMI 2.0 out, PC uses a passive DP to HDMI cable.
Don’t you hate it when there is a bug in your code that magically attracts ads? They just appear without warning or reason.