I have a Mac Mini M1 and I want to verity that it will support 4 unique monitors using the USBC-6950U adapter as follows.
1 monitor connected to Mac Mini HDMI
1 monitor connected to Mac Mini USB-C
2 monitors connected to USBC-6950U
Thank you for inquiring about the USBC-6950U. Given your setup description, assuming you are already acquiring video from your HDMI and USB-C port on your Mac mini, you should be able to use the USBC-6950U to add two additional external 4K displays (via HDMI or DisplayPort) to your system.
Should you elect to move forward with a purchase and find that the USBC-6950U adapter does not meet your needs, Plugable does offer a 30-day no-hassle return policy for all products sold by Plugable and fulfilled by Amazon.