It sounds like PiAware 3 is working correctly and there was something in your setup which was confusing PiAware 2. eth2 on a Pi is pretty bizarre, what did you do to it?
Where is the 00:0f:… MAC of your old site from?
edit: the specific change in the logic was:
I would guess that you have no eth0 so case 1 does not work, and when falling back to case 2, ifconfig vs. ip order the interfaces differently (in particular, ip shows down interfaces, ifconfig doesn’t) and it ends up picking a different one.
It’s yet another reason why we need to move to something other than MAC address for identifying sites, but that is not a short term thing.