Doorbell/ Wi-Fi Offline

As I bought a eufy doorbell recently, the first day the battery died from the factory charge as it was connected to a power supply that had the right specs for the doorbell. As I did charge it and the battery indicator turned gray being connected back to the power supply, witch it didn’t the first time, now it is staying charged as the plug icon is on. Also today my internet company had an outage and we had no internet connection but with the doorbell, the ONLY smart home/Wi-Fi connection device in the house still worked. I do now know how but I was shocked that it was letting me view like view when I had no internet. I further then unplugged the houses router for a reboot and while the router was unplugged and I was on cellular connection I still was able to view live view to the doorbell as I did end up testing if it was “true” live view I was walking in front of it and I was in fact showing up on the live view and clips still was stored locally on the doorbell chime. Like I said I have no clue how that was possible but I was VERY impressed.