HELP with how Indesign, the program, the app, looks on my 4K monitor

I have the latest version -  the most updated version -  of Creative Suite, and I'm using a brand new, super good

super-reliable Windows PC with a top notch graphics card.

I have installed a brand new 43"  4 K monitor.

I've done nothing complicated, other than set up the monitor in the recommended 4K resolution

Photoshop, Illustrator, Premiere, etc. all look stunning.

HOWEVER, Indesign looks "8-bit" when I load the Indesign App, and nothing I can think of or that I can try will change this.

So I'm saying THE PROGRAM ITSELF - Indesign - looks "8-bit".

Any idea what might be going on?