I have a Mac running the latest version of Sequoia and Thunderbird up to date with 140.4.0esr. I have two email accounts. One uses signature text that is entered in Account Settings. The other uses a signature from a file. Boxes are checked for Include signatures for replies and forwards. The issue: When creating, forwarding or replying to an email from either account, it initially inserts the correct signature and looks just fine. But after entering the recipient in the To field, the signature immediately disappears. It happens whether the recipient address is one of my contacts, or is a totally made-up address. I first noticed this happening yesterday. Very strange and very frustrating. Hope I gave you all the details, but let me know on any questions. Thanks for your help!!