According to reddit user, /u/foreverska, FCC ID PL3-100B “Pebble Smart Doggie Doorbell” operates on a frequency of 315 MHz rather than the FCC ID authorized 433.92 MHz.
The schematics indicate CS5211DGO as the transmission chip, as well as the Circuit Description confirming 433.92 MHz operation.
Assuming the device /u/foreverska tested is genuine, it’s likely Pebble Smart altered their designs after FCC ID certification to use 315 MHz for power, cost, or range improvements. This magnitude of a change would require re-certification of the device with the FCC.