I downloaded on your site SyncTrayzorPortable-x64.zip and the SHA1 and SHA512 hashes are correct. But when I check the signature of the files sha1sum.txt.asc and sha512sum.txt.asc themselves with the public key D26E6ED000654A3E given on your site. I have the return that they were signed with another key: FE6ADC8AE112FA6A.
Is this normal since you talk about another older key on your site page ?
gpg --verify sha1sum.txt.asc gpg: Signature faite le sam. 07 août 2021 14:11:16 CEST gpg: avec la clef RSA FE6ADC8AE112FA6A gpg: issuer "email@example.com" gpg: Impossible de vérifier la signature : Pas de clef publique