Rogue software on your phone? Check which apps have permission to read your SMS. This happened to me when I sideloaded Vanced. I did not give it SMS permission,

Rogue software on your phone? Check which apps have permission to read your SMS. This happened to me when I sideloaded Vanced. I did not give it SMS permission, but my number was still added to a database of compromised numbers, and used by all sorts of shady characters for a month or so. Nothing bad happened but I got a lot of recovery and activation emails.