The signing key of the Debian repository is expired.
/etc/apt/trusted.gpg.d/debian.sr.ht.gpg
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pub rsa2048 2019-06-20 [SC] [expired: 2021-06-19]
6B12 96C6 5B24 4726 74E7 B652 0585 B50A C6A4 914D
uid [ expired] SourceHut Debian <debian@sr.ht>