OK, thanks. what you posted is almost like you left out one step. That is, in Disk Utility, click on "View" and then "Show All Devices" and take a shot of that. If you have already done that,then what DU is showing is three devices, all with the hardware name "VendorCo ProductCode Media," each of 2TB size, which is very strange. On that line should be something like what is listed for the boot device at the top of the External section of the sidebar column, where it says ,"WD My Passport 0748 Media." That identifies the actual hardware and the indents under that are the formatted data on that hardware. It almost looks like there is some data missing from the three devices where the vendor code, product code and media code is missing, so the system put in what it did. Can you tell us more about this external set of drives? I must admit that an 8TB SSD is very large, larger than any I've seen thus far, so something is unusual about it.
As an aside, using an SSD as a TM backup is a huge waste of that speed and capability. Backups can be stored nicely on rotating drives because speed is not an issue, normally.