Display Dell U4021qw scrambled into strange tiles

I don't know whether it's the cause or simply coincedence but since the Ventura 13.2.1 update my Dell u4021qw screen has issues. It does connect to my MBP, but once connected, BOTH screens (also the screen of my MBP) scramble into strange tiles. Funny thing: the cursor does display normally, but everything else is scrambled into tiles.

If i use only 80% of the screen by PIP/PBP mode, the issue only persists flickering on my MBP, not on the external screen.

What I've done:

I have connected using thunderbolt & HDMI - issue remains

I used another u4021qw screen - issue remains

I switched cables - issues remains

I have tried other Dell screens (U3821DW) - no issues

I have reset NVRAM/PRAM - issue remains

I already had all the updates available

Specs:

13" MBP 2,4GHz 4Core i5

Intel Iris plus 665 1536 MB

8 GB 2133MHz

Ventura 13.2.1

Firmware Dell U4021qw: M2T102

Does anyone recognise this issue... and is there something I can do about it?

Thank you