My APFS volume group named macOS is corrupted,
so I prepared to erase it to start over. However,
no matter when I attempted to erase it in Disk Utility,
or erase the macOS and macOS - Data volumes one by one,
I always got the error "An internal error has occurred. : (-69623). Operation failed… "
What does it mean?
Does my internal SSD have hardware issues?
What happened to your Mac that made you think your macOS startup volume group is corrupted?
From your description, I can see that you were attempting to wipe your startup volume group in Disk Utility in normal mode.
Since your Mac boots up properly, it doesn’t have serious issues.
If your Mac runs slowly, you can use a Mac cleaning tool to accelerate it.
I’ve used iBoysoft DiskGeeker. This tool has two features for speeding up a Mac.
One is to clean up junk files on Mac, the other is to analyze the space of your startup volume so as to quickly learn which files occupy much storage space.
It is even designed with the AI analysis feature to help you learn whether the file you want to delete can be deleted.
Simply download iBoysoft DiskGeeker.
Select macOS - Data or Macintosh HD - Data (your user data volume).
Click Clean Junk and Space Analyze one by one to clean up your Mac. This is also to accelerate its performance.
If you want to erase your internal drive, you should go to macOS Recovery Mode. You are not allowed to delete volumes you are booted from.
When macOS has errors,
you can run Disk Utility First Aid in Recovery Mode to repair it.
I suggest you do not check, erase, or do other operations on your startup volumes in normal mode.
This will interfere with your Mac’s performance or even lead to system crashes.