Philips Brilliance 279p monitor disconnects randomly from MacBook Pro

The screenshot you showed said the display AND the Mac it was connected to were capable of 3840 by 2160. But this is PROVIDED that the data pathway provided is error-free.

Error-free at top resolutions requires high spec and surprisingly SHORT cables. Cables "shipped in the box" are notorious for being 'lowest bidder' cables, and are often inadequate to support the highest resolutions the display could attain.

certified USB cables for this use should have the older USB SuperSpeed PLUS symbol or better:

.

<<. The two macbook pro are not capable of 4k >>

(max resolution: 1680 * 1050).

Your statement as written is not correct according to the Published specifications for BOTH of those Macs.

However, as I noted, reliable connection over USB-C cables requires certified cables with base capability of at least 10 G bits/second that are appropriately Short.

The USB controller will reverse inbound and outbound lanes to provide about 20 G bits/sec "mostly outbound" connection, which support the 17.18 G bits/sec outbound data rate required for DisplayPort over USB-C -- good for 4K up to 75 Hz, 5K up to 60 Hz, or 6K up to 30 Hz.

I stand by what I wrote above.

When using a USB-C display with resolution as high as 4K, you may send to limit the length of the USB-C cable to ONE meter or less for trouble-free operation.

<<. This is why I suspect a local power supply issue or an electric interference rather than an unreliable capability connection. >>

Have you ruled out interference from badly-shielded third party USB devices ?

Why do I have difficulty with Wi-Fi or Bluetooth devices when USB 3 devices are attached to my computer?

Some USB 3 devices can generate radio frequency interference that can cause Wi-Fi and Bluetooth devices operating in the 2.4GHz band to have issues communicating with your computer. Here are some tips to avoid this issue:

• If your USB device has a cable long enough that you can move the device, place it away from your Mac—and make sure not to place it behind your Mac, or near the hinge of its display. The antennas for Wi-Fi and Bluetooth are located there, and USB 3 devices placed there might interfere with your wireless connections.

• If you're using adapters or dongles on a Mac computer with Thunderbolt 3 (USB-C) ports, plug them into the front port on the left side of your Mac, or into the ports on the right side (if your computer has them). These ports are the farthest away from the antennas, making interference less likely.

• To avoid interference on the 2.4GHz band using Wi-Fi, try using the 5GHz band instead. You can change this on your wireless base station. Bluetooth always uses 2.4GHz, so this alternative isn't available for Bluetooth.

from:

About USB on Mac computers - Apple Support

Resolve Wi-Fi and Bluetooth issues caused by wireless interference

Resolve Wi-Fi and Bluetooth issues caused by wireless interference - Apple Support

but that is a native 3840 by 2160 display!

why are you satisfied to run it at 1820 by 1080?