Yes, you could disable the signature check by editing the code.But this is really not recommended. Only see this a action of last resort if there is no other way to decrypt your files again!
If you edit this file https://github.com/nextcloud/server/blob/master/apps/encryption/lib/Crypto/Crypt.php#L481 and add between L480 and L481 “return true;” This way the signature check will always return true, but as said, that’s not a solution but only something you can do if nothing else helps.