Mac Mini M4 compatible with Dell S2722QC monitor?

What port on the Mac mini are you connecting the monitor to exactly?

The USB-C port on the monitor is a Display Port 1.4 version which would require you plug it in to one of the rear Thunderbolt ports on the Mac. If plugged into the front USB-C ports it won't provide a video signal.

Alternatively, you can use an HDMI cable instead.

https://dl.dell.com/manuals/all-products/esuprt_electronics_accessories/esuprt_electronics_accessories_monitor/esuprt_monitor_s_series/dell-s2722qc-monitor_user's-guide_en-us.pdf

Dell – Dell 27 4K UHD USB-C Monitor - S2722QC

That's a 27" monitor with a resolution of 3840x2160 pixels and a refresh rate of 60 Hz. It has three video inputs: a USB-C (DisplayPort) one, and two HDMI ones. It comes with a USB-C to USB-C cable.

My guess is that Phil has identified the issue: plugging the display into one of the front-panel ("USB-onlly") USB-C ports on your Mac mini. A more remote possibility is that the bundled cable is not of very high quality and the Mac is deliberately cutting off the signal due to detection of display transmission errors.

Not sure what cable came with the monitor but if it has a DP then you will need a USB (or thunderbolt) to DP adapter or as already stated use the HDMI port.