Something is suddenly not clear about Time Machine external drives. And I'm also unclear on how one can tell whether an external drive is encrypted.
My current active Time Machine drive (for my 2017 iMac, Catalina) does not ask me for a password before mounting, if I plug it into my M2 Mini (Ventura). That would seem to indicate that it doesn't have volume-level encryption.
(Although I do occasionally get a password dialog for that drive, during the iMac boot process.)
But if I go to the Time Machine control panel, click "Select Disk," and click on the active Time Machine drive, "Encrypt backups" is checked. And if I click on another drive, to which I just today copied the contents of the active Time Machine drive, "Encrypt Backups" is not checked.
That leaves me scratching my head.