External monitor flickering with new MacbookPro M4

your displays appear to be 1920 by 10180 and 8 bis color Millions of colors, NOT HDR)

interfaces include Analog VGA and DisplayPort.

Your dock appear to be a genuine Thunderbolt Dock, which the Mac supports for two displays as long as they are not too large.

DisplayPort cables for modern displays should ONE meter or shorter for maximum reliability (such as no flickering).

<< The flickering and the stripes stay on the screen even if I unplug the macbook and e.g. connect my old laptop. >>

If you have all that other stuff in spec, including cable lengths, that really sounds like a problem inside the display. do BOTH displays do this equally? Will swapping displays with each other give any different results?

I have also the M4 Pro, 24Gig with 1TB to replace my M2 Pro 16Gig. External monitors: 32Inch 4k LG and a 40Inch 4k Samsung. Flickering occurred with the following settings:

Main Display: Samsung

Lg 4k mirror for Samsung

Built-in Display: Mirror for Samsung

All optimize for Samsung.

All Displays set to Full Screen(Note: if all displays are not set to full screen, flicker becomes minimal to negligible)

If I close the MacBook display, flicker stops whether the displays are in full screen or not.

If I set all to Optimize for the built-in Display, the built-in display experience severe flickering while the other two external monitors still show random flickering which is still unacceptable.

I tried setting all refresh rates the same for all but to no avail. I have been working on this issue for almost 24 hours now and still have not found any solution.

Big note: Given same settings, displays and cables and connections, my old M2 does not experience the same flickering at all! I am still in the return window so I may have to return this M4 as this issue is unacceptable.

<< adapter (usb-c to 2x display port). >>

what make and model adapter, exactly?