U3223QE, MacBook Pro 14” M1 2021, no picture

Hi Stefan,

Have you tried using a different HDMI cable or connecting the MacBook Pro to a different monitor to see if the issue is with the cable or the monitor? It's also worth checking if the HDMI port on the monitor is working properly by connecting a different device, such as a gaming console or a Blu-ray player.

If the issue persists, you can try resetting the monitor to its factory settings by navigating through the monitor's OSD (On-Screen Display) menu. You may also want to check if there are any firmware updates available for your monitor on the Dell website.

If none of these solutions work, it may be worth contacting Dell support for further assistance.

I hope this helps!