In one of the example for $hour (aggregation) documentation, the result is 18.

{ $hour: {
    date: new Date("August 14, 2011Z"),
    timezone: "America/Chicago"
} }

However the correct result should be 19. Running in the same in old (legacy) mongo shell gives 18. This is because that syntax is wrong for mongosh and the date becomes ISODate("1970-01-01T00:00:00Z")

Discussion on Slack: https://mongodb.slack.com/archives/CC1SW4PA4/p1693242762226949