For a while there's a weird issue in my network that some of the devices would randomly get a weird IP that's not in the same subnet as my other devices, and unifi's rogue dhcp server detection never fire so I thought it's some unifi DHCP server bug.
It turns out to be actually a rogue dhcp server: The builder installed SPAN's electricity panel and wired the ethernet to the media closet, and I plugged it into the switch. But on SPAN's side they plugged into the wrong port 🤦