We purchased a handful of 16inch and 14inch M1 MBP's. We have been pairing them with three different 4k monitors. HP, LG non HDR, LG HDR. The HP and LG non HDR have very little flicker or vertical lines but the LG HDR has been a mess. Keep in mind, we had previous generation MBP's connected with all the same cables and monitors with no issues and many of us also have Windows laptops or desktops for different kinds connected to these same monitors / different inputs with no issues.
The LG HDR monitors flicker like crazy unless we turn HDR in Display Settings on the MBP for the external display. As soon as we do that, no flicker from the MBP's with the LG HDR monitors.
We have tried MANY different USB-C to Display and USB-C to HDMI all with the same results. HDMI to HDMI we haven't seen the issue but we also have been focused on USB-C cables since we had so many from our 2020 Macbook's and all our employees use dual monitors in addition to the laptop screens.
I'm old school and play Startcraft 2 on the M1 MBP. When playing on the LG HDR external display without HDR enabled Starcraft flickers allot and it has the vertical lines. Certain menus within the game cause it as well. In Monterey, when we move windows around or off the screen we can reproduce the same issues. The problem seems to be lighting, shading or certain textures.
Fortunately with so much equipment to test dozens of scenarios were able to find some solutions but Apple really needs to fix this. We have seen no improvements change display rates or monitor settings or factory resetting monitors etc. We really tired everything!
Hope this helps others who are seeing issues. Other than the external screen problems the new MBP's have been fantastic in every other way.
Tim
