Comment # 5 on bug 108031 from Alexander Schlarb

Using the latest Debian kernel (4.19.0-2, which apparently corresponds to Linux
version 4.19.16, with 4.19.0-1 having corresponded to 4.19.13) this issue does
not affect me anymore.

I looked through the kernel commits between the versions but none looked very
related, there was some stuff about DP MST which maybe somehow relevant since
the display is connected using eDP. Dunno.

Anyways, works for me now.