timeShift() function not adding accurate time to _start and _stop

Hi
I was trying out the timeShift() function and according to the documentation the duration is "The amount of time to add to each time value" this seems to be the case for the _time column but for _start and _stop it does not seems to add the correct amount of time. I made the following time shift queries on my data:

timeShift(duration: 0s, columns: ["_start", "_stop", "_time"])
timeShift(duration: 1s, columns: ["_start", "_stop", "_time"])

In the table below the first row is 0 s time shift and the second row is 1 s time shift. As you can see it is correct for _time but for _start and _stop it looks like it adds something like 32 seconds

_start                      _stop                       _time
2021-04-19T07:54:11.063Z    2021-05-19T07:54:11.063Z    2021-05-11T13:02:14.808Z
2021-04-19T07:54:43.842Z    2021-05-19T07:54:43.842Z    2021-05-11T13:02:15.808Z

I hope I have not misinterpreted something.

Start by reproducing the two timeShift() queries from the report with the same _start, _stop, and _time columns. Trace how duration is applied to each column and verify that a 1s shift changes all three timestamps by exactly one second.