Why does my Mac/PC only work with 1 display?
Mac Book Air, Mac Book Pro 13” and Mac Mini with an M1 or M2 processor support only 1 external display over Thunderbolt.
Make sure your systems are updated to the following versions:
My 8K does not work on my Mac after updating to OS 11.X (Big Sur)?
Unfortunately, Macbook OS 11.X (Big Sur) does not support 8K displays.