Details about the (ongoing) response to https://gpg.fail/ from GnuPG's side:
* https://www.gnupg.org/blog/20251226-cleartext-signatures.html
* https://dev.gnupg.org/T7906 Memory Corruption in ASCII-Armor Parsing
* https://dev.gnupg.org/T7900 (overview)
Please upgrade to GnuPG 2.5.16, 2.4.9 or #Gpg4win 5.0.0-beta479 which already have the fix for what (currently) is seen to be the only major defect: T7906.
(Researchers - Thanks! - found defects in GnuPG, Sequoia-PG, Minisign and age.)