I thought the same, but I was not sure, so I searched for the answer, and surely the NIST page "Daylight Saving Time Rules" [1] would be definitive? Unfortunately, its statement of the rule [2] seems ambiguous, in that it uses '2 a.m.' without qualifying it as local time (though the example does.) Is there a rule saying that times expressed as a.m. (or p.m., I suppose) are always local time (in whatever context they appear, which could also be a cause of ambiguity) unless explicitly qualified otherwise?
[2] At present, daylight saving time in the United States begins at 2:00 a.m. on the second Sunday of March (at 2 a.m. the local time time skips ahead to 3 a.m. so there is one less hour in that day) [and] ends at 2:00 a.m. on the first Sunday of November (at 2 a.m. the local time becomes 1 a.m. and that hour is repeated, so there is an extra hour in that day.)
2 am local time is the transition time. Some days you go from 1:59 am standard to 3:00 am daylight, others you go from 1:59 am daylight to 1:00 am standard.
It's not like leap seconds which are added (or hypothetically removed) at a specific universal time, so whatever your time zone, whatever minute corresponds with utc 23:59 gets an extra second.
[1] https://www.nist.gov/pml/time-and-frequency-division/popular...
[2] At present, daylight saving time in the United States begins at 2:00 a.m. on the second Sunday of March (at 2 a.m. the local time time skips ahead to 3 a.m. so there is one less hour in that day) [and] ends at 2:00 a.m. on the first Sunday of November (at 2 a.m. the local time becomes 1 a.m. and that hour is repeated, so there is an extra hour in that day.)