Since updating Thunderbird to 102.3.2, it shows "This is an encrypted OpenPGP message, but support for OpenPGP decryption is not available" for completely unencrypted emails. Viewing the message source show that there is no encrypted part and this way I can actually read my mails the hard way. This happens for different mails from different senders, but not all mails are affected. I can not share the message source as its impossible to attach it here in the form (only images are accepted). Let me know if I can be of any help, providing a mail to reproduce or such.