GPS satellites probably handle it well too, but maybe some consumer or even industrial GPS receivers don't? Maybe some trading systems? I don't think crypto systems care too much.
But the meter/reporting tool would say "Well, we measure every second, and the meter reported a constant rate of 100 liter/second, and as we know we have 60 seconds in a minute, so we got 6000 liters!".
Or a database for "measurements every second for this minute" that has 60 fields, and don't have a field for the 61st measurement.
Like how much time is there between 2 and 3 am? Usually one hour, but sometimes 2 and also sometimes 0. It looks simple at first but it creates a lot of edge cases that your business logic now needs to handle and we had a fairly complex system for this.
My son is born at 02h30 right DST change time.
It tooks 3 f*cking days to get his birth registered in the Hospital new birth registration system.
The hospital (at the time) just got digitalized and most systems where not able to agree if he was born after or before DST changes.
PS: I guess he is born fated to be a software QA later on.
Though if it's valuable enough it could of course be "worth" paying top dollar to have engineers solve a ludicrous non-issue.
Was involved in rolling out a large NTP annealing patch about ten years ago. We missed a couple and the effect was largely overall muted, but we did have one server with an old JVM hard crashing the server right at the second shift.
That specific server was already hobbling along so it wasn't a surprise. But it required a bit of firefighting.
I've worked on some extremely sensitive systems that had thousands of lines of C dedicated to handling skewing a time gap across an hour-per-second when necessary. I know that code assumed only "missing" time (jump-forwards)... Even knowing what I know as a developer now, if I was re-implementing that system from scratch and didn't have this top-of-mind, I'd bet I would miss "overlapping" or "duplicate" time entirely.
Maybe that is more of a me problem than others, but I'd bet there are some safety critical systems out there where the responsible engineers, QA, and specs all missed this as well.