Odd styling on fresh install

[TimoRoth]

I'm currently trying to spin up a slightly "odd" way of running JupyterHub/TLJH/repo2docker: Inside of docker
However, I ran into an issue which I don't think is really related to that way of setting it up, since everything else seems to be working great.

Namely, my service page looks like this:

There are no errors logged, nothing.
The HTML page also looks identical to the one of our (slightly outdated) production instances.

However, what does strike me as different is how Bootstrap appears to have been updated from Bootstrap v3.4.1 (on our production instance) to v5.3.3 without many changes on the HTML layout. Which would definitely explain why the sites styling largely broken.

It works fine however! I can manually navigate to the environments page, and build an environment just fine.
I could not find where bootstrap or other web-dependencies are coming from.

If you want to give this specific setup a try easily, it's here: https://github.com/TimoRoth/TLJH-Docker
Just running the update script on any modern docker installation should leave you with a fresh install running on localhost:8000, with environments isolated from the host.
Again, I really don't think this issue is related to this way of running TLJH, given everything else works perfectly.