Firebase server-timestamp differs from the correct time

I am trying to use firebase-server-timestamp to show the user when he/she send their order to us.

The problem I encounter is, that the server-timestamp is showing a wrong time (e.g: Current time is 12:30, but timestamp shows 12:15). How is that possible?

Android code

data class MyTimestampPOJO(
    val date: Timestamp = Timestamp.now(), // wrong, 15 minutes too early
)

Database screenshot (sending was at 12:50 and not 12:35)

I am testing this inside the firebase-emulator. The time on my phone is correct (even tho it does not matter, because the server-timestamp is independent to the phone-time, as it should be.)

from Firebase server-timestamp differs from the correct time