Just to pick a couple from last year that are unambiguous and well-documented (most you’ll have at least a bit more trouble finding first-party announcement of):

2021d: Fiji gave a month’s notice on suspending DST for the season.

2021b: Samoa gave less than a week’s notice on cancelling DST.

I have a feeling there was a less-than-two-days’ notice a few years ago, but can’t be bothered hunting for it. But there are many more of things like “eh, we’re shifting the start or end by a day or two or a week or two, with less than ten days’ notice”.