MacBook Pro's LG UtraGear monitor reverts to quadrants on wake

HDMI cables you want for HDMI-only Displays (higher resolutions than 720p TV sets) are marked as Certified with an anti-counterfeiting tag and are labeled:

"PREMIUM High Speed HDMI cable" or that + "with Ethernet" (up to 4K at 30Hz) --OR--

“ULTRA High Speed HDMI cable" or that + "48G" (supports higher resolutions and backward-compatible)

Cables with No Certification tags are good for your standard 720p TV set, and not much more.

Cables 'shipped in the box' with many displays can be "lowest bidder" cables that are not up to high-end display use. Cables with no markings 'found' behind your TV set are unlikely to be good enough.

HDMI was invented for HD TV sets. it works great at its original resolution of 720i or 720p. At higher resolutions, it quickly develops issues that are complex to solve, and the cables and adapters required to solve are NOT intuitive.

After thinking about this more, it might be related to settings inside the display, when you have multiple display inputs in use (your Mac, your HP,...). Perhaps it is showing you the multiple data streams, and inviting you to pick one.

Some displays have settings where one input is considered Primary, and will be used unless you take steps to select another.

LG 52G930B-B appear to be a 5120 by 2160 display, like a 5K display with the bottom part missing. it accepts 10 bits/color and refresh rates to 240 Hz. includes Picture-By-Picture capability

interfaces include:

2x HDMI 2.1

Displayport 2.1

USB-C with 90 watts Power delivery, BUT lower direct maximum resolution and refresh rates

¿What cables, adapters and racks are you using to make the connection?

if you are using appropriate cables, this symptom may be caused by settings inside the display. It has NOT been widely reported here.