Because the power supply from the PD restarts through the PoE's normal operation of Detection → Classification → supply of 48V power from the PSE when the power supply from the adapter is discontinued, power cannot be supplied for a certain period of time.
On the other hand, continuous power supply is possible by using a circuit as shown in the attachment, because the PD operates continuously even if the power supply from the adapter is stopped.
However, an R1 that satisfies the MPS requirements is required.