Pro Max 16 Plus MB16250, SD25TB5 dock, flickering in Linux

My external display (an Eizo CX240) constantly flickers on Linux desktop (KDE plasma running on Wayland), when attached to my SD25TB5 dock (doesn't matter whether connected via DisplayPort or HDMI). The flickering starts as soon as the KDE task manager is started. It appears to temporarily stop, when there is any movement on the display (e.g. while I move the mousepointer on that display). Main display is laptop screen; I extend the desktop onto my external display.

No issue in Windows 11 Pro => external display works as-expected (both on DisplayPort and HDMI).

No issue when connecting the external display via HDMI directly to the laptop's HDMI output (laptop does not have a DisplayPort output, so can't test that).

From this, I conclude that issue is not with cabling nor with display itself, but probably with an issue between Linux and the SD25TB5 dock. Is this a known issue? Is there a way to fix this?

Some more context:

Laptop is a Dell Pro Max 16 Plus laptop (MB16250) with OLED display and integrated Intel graphics.
Dual boot is set up for Windows 11 Pro and Tuxedo OS (a Linux distro (kernel 6.14) based on Ubuntu, but using KDE plasma desktop).

At home, I connect the laptop to a SD25TB5 dock via one of the TB5 ports on the laptop.
I connect my Eizo CX240 display to the SD25TB5 dock via a DisplayPort cable.

I updated the firmware of both the laptop and the dock using SupportAssist app from Windows.