It looks like your signing key is expired, and tag verification fails:
$ mkdir /tmp/foo
$ export GNUPGHOME=/tmp/foo
$ git cat-file blob junio-gpg-pub | gpg --import
gpg: WARNING: unsafe permissions on homedir '/tmp/foo'
gpg: keybox '/tmp/foo/pubring.kbx' created
gpg: key 20D04E5A713660A7: 27 signatures not checked due to missing keys
gpg: /tmp/foo/trustdb.gpg: trustdb created
gpg: key 20D04E5A713660A7: public key "Junio C Hamano <gitster@xxxxxxxxx>" imported
gpg: Total number processed: 1
gpg: imported: 1
gpg: no ultimately trusted keys found
$ git tag -v v2.33.0
object 225bc32a989d7a22fa6addafd4ce7dcd04675dbf
type commit
tag v2.33.0
tagger Junio C Hamano <gitster@xxxxxxxxx> 1629141357 -0700
Git 2.33
gpg: WARNING: unsafe permissions on homedir '/tmp/foo'
gpg: Signature made Mon Aug 16 15:15:57 2021 EDT
gpg: using RSA key E1F036B1FEE7221FC778ECEFB0B5E88696AFE6CB
gpg: Good signature from "Junio C Hamano <gitster@xxxxxxxxx>" [unknown]
gpg: aka "Junio C Hamano <junio@xxxxxxxxx>" [unknown]
gpg: aka "Junio C Hamano <jch@xxxxxxxxxx>" [unknown]
gpg: Note: This key has expired!
Primary key fingerprint: 96E0 7AF2 5771 9559 80DA D100 20D0 4E5A 7136 60A7
Subkey fingerprint: E1F0 36B1 FEE7 221F C778 ECEF B0B5 E886 96AF E6CB
$ echo $?
1
Have you extended the expiration on it? I wasn't able to find any
updates on the keyservers I checked. But regardless, we should probably
ship an updated one via the tag.
-Peff
