xrandr --setprovideroutputsource 1 0 fails on Bunsenlabs Beryllium

I am trying to connect two monitors to my Lenovo X1 Carbon Gen 10 using a Lenovo dock (Type 40AF). I am running Bunsenlabs Beryllium (I know, not supported. This may be my issue?), but if I forge ahead as if I knew what I was doing:

> jpc@krazykat:~$ git clone https://github.com/AdnanHodzic/displaylink-debian.git

fails with:

> Unsuported platform: Bunsenlabs bullseye
> Full list of all supported platforms: http://bit.ly/2zrwz2u
>

Hmm... well, Bunsenlabs is *almost* Debian, so I tried simply editing displaylink-debian.sh to hardwire lsb="Debian", and tried again:

> jpc@krazykat:~/displaylink-debian$ sudo ./displaylink-debian.sh

Seems to succeed and ends with:

> Install complete, please reboot to apply the changes
> After reboot, make sure to consult post-install guide! http://bit.ly/2TbZleK
> Reboot now? [Y/n]

After rebooting I run

> jpc@krazykat:~/displaylink-debian$ sudo ./displaylink-debian.sh --debug
>
> -------------------------------------------------------------------
>
> Starting Debug ...
>
> Did you read Post Installation Guide? http://bit.ly/2TbZleK [y/N] y
>
> Did you read Troubleshooting most common issues? http://bit.ly/2Rofd0x [y/N] y
>
> --------------- Linux system info ----------------
>
> Distro: Debian
> Release: bullseye
> Kernel: 5.18.0-0.deb11.4-amd64
>
> ---------------- DisplayLink info ----------------
>
> Driver version: 1.12.0
> DisplayLink service status: up and running
> EVDI service version: 1.12.0
>
> ------------------ Graphics card -----------------
>
> Vendor: i915
> Subsystem:
> VGA: Intel Corporation Device 46a6 (rev 0c)
> VGA (3D):
> X11 version: 1.20.11-1+deb11u6
> X11 configs: /etc/X11/xorg.conf.d/20-displaylink.conf
>
> -------------- DisplayLink xorg.conf -------------
>
> File: /etc/X11/xorg.conf.d/20-displaylink.conf
> Contents:
> Section "Device"
> Identifier "Intel"
> Driver "intel"
> EndSection
>
> -------------------- Monitors --------------------
>
> Providers: number : 1
> Provider 0: id: 0x4b cap: 0xb, Source Output, Sink Output, Sink Offload crtcs: 5 outputs: 7 associated providers: 0 name:Intel
>
> -------------------------------------------------------------------
>
> Use this information when submitting an issue (http://bit.ly/2GLDlpY)
>
> -------------------------------------------------------------------
>
> jpc@krazykat:~/displaylink-debian$ xrandr --listproviders
> Providers: number : 1
> Provider 0: id: 0x4b cap: 0xb, Source Output, Sink Output, Sink Offload crtcs: 5 outputs: 7 associated providers: 0 name:Intel
>
>
>

So I only seem to have one provider (and I notice it says "Source Output, Sink Output, Sink Offload")
. I tried the suggestions in the Post Installation guide that mention problems like this with an intel card. FIrst I changed /etc/X11/xorg.conf.d/20-displaylink.conf to contain:

> Section "OutputClass"
> Identifier "DisplayLink"
> MatchDriver "evdi"
> Driver "modesetting"
> Option "AccelMethod" "none"
> EndSection
>

which led to 3 providers

> jpc@krazykat:~$ xrandr --listproviders
> Providers: number : 3
> Provider 0: id: 0x49 cap: 0x2, Sink Output crtcs: 4 outputs: 6 associated providers: 0 name:modesetting
> Provider 1: id: 0x127 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
> Provider 2: id: 0x105 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
>

but none of them were a Source Output, which may have led to the problem below:

> jpc@krazykat:~$ xrandr --setprovideroutputsource 1 0
> X Error of failed request: BadValue (integer parameter out of range for operation)
> Major opcode of failed request: 140 (RANDR)
> Minor opcode of failed request: 35 (RRSetProviderOutputSource)
> Value in failed request: 0x49
> Serial number of failed request: 17
> Current serial number in output stream: 18
> jpc@krazykat:~$
>

I also tried the following /etc/X11/xorg.conf.d/20-displaylink.conf:

> Section "Device"
> Identifier "DisplayLink"
> Driver "modesetting"
> Option "PageFlip" "false"
> EndSection
>

as well as removing /etc/X11/xorg.conf.d/20-displaylink.conf altogether, but all resulted in the same behavior.

Any suggestions as to how to begin debugging this? Is there any more info I can provide to help?