I am basing the statements on what HAS/DID happen to me.
I fluffed up and did something I shouldn't have.
I had a backup - be it 5 months old. Nothing had changed.
Trying to load the backup caused problems with a stored MAC address having -
rather than :
in it.
So I eventually got that part fixed, imported the backup (I think it was PiHole 5) and there were no blocked lists given.
This gave rise to me posting multiple requests asking why PiHole wasn't working.
I've now got it working - thankfully.
And the list of blocked sites has kinda grown, but that's beyond the scope of this.
I'll export the settings again so if ever this happens again, I will - I hope - have a working version of the backup to get back to.
Now, here I'll accept I am going a bit off topic.
This Incorrect MAC address issue.
I started using PiHole about the same time I totally rebuilt my home network.
The ROUTER, SWITCH and a WAP were all in the picture.
I'm not EXACTLY sure how I got the MAC addresses for ALL the devices, but I'd guess from the ROUTER, as it is the BIG BOY in the scheme of things and shows me all device's MAC addresses.
I would see the MAC address, drag the mouse over it, copy and paste it into PiHole's list.
That was..... 4 years ago.
NOT ONCE in the past 4 years has PiHole complained about the INCORRECT MAC address, and it has been rebooted a few times - as much as I would like to have run for that long nonstop.
So - to me - there is a problem that slipped through the cracks that allowed me to enter this WRONG MAC ADDRESS, way back when, and the first time I was told was a few weeks ago when all this stuff hit the fan.