Dear maintainer(s),

I noticed that package python3-smart-open recommends
python3-backports.zstd, which is not in unstable. I've checked via
tracker.debian.org and packages.debian.org and it does not exist or have
existed (for what I can tell) python3-backports.zstd binary.

What it had existed is python-backports.zstd
(https://tracker.debian.org/pkg/python-backports.zstd) but it was
removed in 2029-09-18 because this is not needed since Python 3.13,
according to https://tracker.debian.org/news/1797464/python-backportszstd-removed-from-testing/

I think that the Recommendation can be just dropped based on that.

PS[0]: I am developing a tool to detect such issues:
https://salsa.debian.org/carlespina/check-relations . Reports are
manually reviewed before submission. If you would prefer not to receive
such reports (for specific packages, all of your maintained packages,
etc.), please let me know. Any other feedback is welcomed as well. No
more bugreports for this missing relation will be sent.

PS[1]: more information available in
https://salsa.debian.org/carlespina/check-relations/-/blob/main/README.md
and
https://salsa.debian.org/carlespina/check-relations/-/blob/main/docs/bug-report-extra-info.md