iMac (Retina 5K, 27-inch, 2019) Format of Macintosh HD in Big Sur

I maintain three desktop Macs. All run the latest version of macOS 11.

They are:

1. 1. iMac (Retina 5K, 27-inch, 2019)
   2. iMac (Retina 5K, 27-inch 2014)
   3. Mac mini (m1, 2020)

All have an internal 1T SSD.

This question regards Number 1 on the above list.

After I did a clean install and restored the boot drive from Time Machine, Disk Utility reported its structure as follows:

1. 1. iMac (Retina 5K, 27-inch, 2019)

Disk Utility Reports: PCI-Express Internal Physical Disk - GUID Partition Map

I did the same for the older iMac, and Disk Utility reported its structure as follows:

2. iMac (Retina 5K, 27-inch 2014)

Disk Utility Reports: APFS System Snapshot - APFS

Finally, the M1 Mac mini, which is formatted as it came from the factory, is as follows:

3. Mac mini (m1, 2020)

Disk Utility Reports: APFS System Snapshot - APFS

NOTE: "1. iMac (Retina 5K, 27-inch, 2019)" has an internal 1T SSD, not a Fusion Drive. I do not know why Disk Utility reports it as having a "PCI-Express Internal Physical Disk."

I ran Apple Hardware Diagnostics on the iMac (Retina 5K, 27-inch, 2019), which reported it as being fine.

"iMac (Retina 5K, 27-inch, 2019)" suffers the occasional kernel panic, which I generally find to be a very rare occurrence on Macs. The last kernel panic was about five days ago.

Questions:

1. Is, as I suspect, "1. iMac (Retina 5K, 27-inch, 2019)" defectively formatted, and should I wipe it and reformat it yet again?
2. If yes, how best should I do that?

If the answer is yes, I will leave to philosophers the question of how this happened.

P.S. For the record, "1. iMac (Retina 5K, 27-inch, 2019)" ran very well until I upgraded it to Catalina last year. The SSD suffered a weird formatting issue that drew in ever-increasingly senior Apple help personnel, until they found a solution. I do wonder if this problem is related to that one.