FTR, the issue is related to our version of reprepro not supporting zstd compression
It was introduced at: ``` reprepro (5.3.0-1.3) experimental; urgency=medium
* Non-maintainer upload. * Add support for Zstd compressed debs. (LP: #1923845)
-- Dimitri John Ledkov xnox@ubuntu.com Mon, 21 Jun 2021 10:16:53 +0100 ```