“Other Volumes” taking up 300gb in Bug Sur beta

[jec0047]

Was it this one?

Why are there 3 disks on macOS?

Take a look at this screenshot of my MBA’s Disk Utility: [Screen Shot 2020-10-14 at 19.20.18] It shows that there are ~45 GB of disk space that is taken up by an unmounted volume on the left sidebar (bottom one in the list). Why are there three? I know Catalina separated user data + system data, but that’s two disks. Did I miss something? Are there supposed to be 3, and if so, what is the third one?