No display on ThinkPad USB 3.0 Pro Dock

[udippel]

I used to run my systems (lenovo Helix 2) via USB 3.0 Pro Docks; lid closed, display only on the external monitors without problems, until bug [Bug 1871959] Re: Crash with SIGABRT in _iris_batch_flush from iris_fence_flush() made the DisplayLink unworkable.
Now, with this bug being squashed, it doesn't crash any longer, but simply doesn't show anything; not even detecting the (various) monitors any longer (System Settings).
To me, that's no progress (rather regress), since it used to work flawlessly earlier.

$ ubuntu-bug mesa
dpkg-query: no packages found matching mesa

$ dpkg -l | grep mesa
shows a bunch of 22.2.5-0ubuntu0.1~22.04.1 packages.

$ xrandr
HDMI-{1|2} disconnected (normal left inverted right x axis y axis)
HDMI-1 is the display device that shows when connecting to the mini-DP-connector in the tablet.

[Kai-Heng Feng (kaihengfeng)]

Is it possible to give 21.04 a try?