MacPro 2019 + DELL U4021QW – display flickers

Mac Pro 2019, newest OS, newest CC versions.

Since a few days (now with DELL U4021QW + 2 LG 24MP88HV), before with (LG_38 UC99 + 2 LG 24MP88HV) the Dell flickers, esp. when using InDesign.

Here’s a video:

https://www.dropbox.com/s/su9lfgawckpvegf/IMG_3038.MOV?dl=0

Also some strange photoshop behavior.

SAME file, zooming in and out:

https://www.dropbox.com/s/m1hdxvnp9wjlskp/IMG_3040.mov?dl=0

Has someone pleeease an explanation for me…