Weird status of pdm

Hello.

I would like to get some help with "pdm". The package builds fine in salsa ci:

https://salsa.debian.org/python-team/packages/pdm/-/pipelines

but it fails in the buildds:

https://buildd.debian.org/status/package.php?p=pdm

Recently, Graham Inggs told me that many python packages are expected
to FTBFS during the transition (to avoid MBF for issues that will fix
by themselves), so I wonder if this is one of them or not.

I feel that there must be something subtle about this case and I don't
know what it could be.

Thanks.