Signal Desktop now includes support for a new “Screen security” setting that is designed to help prevent your own computer from capturing screenshots of your Signal chats on Windows. This setting is automatically enabled by default in Signal Desktop on Windows 11. If you’re wondering why we’re on...
Reading their other comments, i think they are not using a real number/a number they don’t have access to, and signal is requiring to verify it/ “secure it” after the update. Thus, even tho the messages are stored locally they can’t access it without doing something with the number