In a calculation involving TimeObjects I noted that the addition of a time quantity to a TimeObject behaves differently depending on whether the TimeZone of the TimeObject is equal to the current $TimeZone or not.

For example the addition of 1 hour to a TimeObject with no explicit TimeZone

TimeObject[{12, 0, 0}] + Quantity[1, "Hours"]

yields the expected result (given in InputForm):

TimeObject[{13, 0, 0}, "Instant", None]

Similarly, when the TimeZone is set to the local TimeZone (in my case $TimeZone is 1.):

TimeObject[{12, 0, 0}, TimeZone -> $TimeZone] + Quantity[1, "Hours"]

yields (again in InputForm):

TimeObject[{13, 0, 0}, "Instant", 1.]

However, if a TimeObject in a TimeZone different from the local TimeZone (here: Tokyo) is used

TimeObject[{12, 0, 0},TimeZone -> LocalTimeZone[Entity["City", {"Tokyo", "Tokyo", "Japan"}]]]

which has the representation

TimeObject[{12, 0, 0}, "Instant", "Asia/Tokyo"]

adding one hour to it like

TimeObject[{12, 0, 0}, TimeZone -> LocalTimeZone[Entity["City", {"Tokyo", "Tokyo", "Japan"}]]] + Quantity[1, "Hours"]

does not yield, as I would have expected, 13 pm but instead (once more in InputForm):

TimeObject[{5, 0, 0}, "Instant", "Asia/Tokyo"]

What am I missing here?