Disk Utility Container Disk
I’ve seen Container disks go up in numbers but mine is up to Container disk20 is that excessive?
"disk20" is just the drive identifier macOS uses to identify various physical drives, partitions, Containers, and volumes. If you had a lot of external drives connected at the time you booted this Mac (or any devices which may have its own storage accessible from macOS such as an iPhone), then it can cause this number to be large since the Mac will begin enumerating the physical drives followed by Containers & volumes. Same thing may happen if you are booted into Recovery Mode especially if you just erased the SSD/Container since there are dozens of virtual volumes when booted into recovery mode each of which receives its own drive identifier.
