USB-C to Display Port (cable straight from the Mac mini to the display - no hubs or anything). I've had this issue since I bought my Mac mini M1. In some cases, a 4K monitor is only recognized as a 1080p monitor. The second issue results in resolution issues with external displays unable to work at a full 4K 60Hz resolution, instead locked at 30Hz. It's almost as if the signal for the monitor to turn on is not being sent.
MacOS appears to recognize the monitor and resolution, as it is shown in display settings, and Apple Support was able to remove into my computer and see both screens. Secondary monitor (same model) connected via HDMI->DisplayPort adapter (BENFEI), then DisplayPort->USB-C cable no longer works after updating (worked fine on 11.1 before updating). Primary monitor LG Ultrafine 4k (Mac version) connected via Thunderbolt. Upgrading to 11.2 broke my second external monitor connection. We saw this issue firsthand after upgrading a MacBook Pro to macOS Big Sur 11.2, with the update preventing an external monitor from connecting with USB-C, and there are several other complaints from affected users. Apple support had no fix, so I guess I'll wait on 11.3 to fix the 11.2 update which was supposed to fix external monitor issues. I have lost my second monitor and can only use HDMI now. Warning - Big Sur 11.2 update is breaking USB-C ports for many.
