Apple has acknowledged problems experienced when using an M1 Mac with ultrawide or super-ultrawide external monitors.

M1 Macs don’t seem to recognize the native resolution of these monitors …

Macworld spotted an extremely brief support document.

If the supported resolution isn’t available on an ultrawide or super-ultrawide external display connected to your Mac with Apple M1 chip

If you connect an ultrawide or super-ultrawide monitor to your Mac with Apple M1 chip, some resolutions supported by your display may not be available.

Apple is aware of this issue and resolution is planned for a future macOS update.

To see the additional resolutions for your external display, choose Apple menu  > System Preferences, click Displays, then press and hold the Option key while you click Scaled.

The final line suggests, but doesn’t promise, that you might be able to enable a more appropriate resolution through the scaled options, but it’s unclear whether that might include the native resolution.

One of our readers found a fix for his issue.

Personally, I’m a huge fan of super ultrawide monitors, ending up with the Dell UltraSharp 49-incher.

Source: 9to5mac