Unexpected result for `diff` over DateTime range

General Usage
2

Please use the latest Julia version (1.8.0)

julia> a = Dates.DateTime("2019-01-01T00:00:00"):Dates.Year(1):Dates.DateTime("2020-01-01T00:00:00")
DateTime("2019-01-01T00:00:00"):Year(1):DateTime("2020-01-01T00:00:00")

julia> diff(a)
1-element Vector{Millisecond}:
 31536000000 milliseconds