The timestampsInSnapshots option has been around for a while but it is deprecated and now is enabled by default.
Version 5.8.0 - Jan 17, 2019
BREAKING: The timestampsInSnapshots setting is now enabled by default. Now, timestamp
fields read from a DocumentSnapshot will be returned as Timestamp objects instead of Date.
Any code expecting to receive a Date object must be updated.
The timestampsInSnapshots option has been around for a while but it is deprecated and now is enabled by default.