What seems to have happened is that a relatively new non-local mapper has tried to “fix” the border here (because the USA and Canada borders didn’t align, presumably due to the dispute that the Wikipedia link mentions).
The affected relations were the USA, Alaska, and two lower-level Alaska relations, Ketchikan Gateway and Unorganized Borough. The last two relations were actually broken in the process and have since been restored by another mapper.
The net result seems to be:
Note that there are node and way changes made in those changesets too. A “simple revert” isn’t an option, because among other things some of the relations concerned have had valid edits since.
Assuming that the changes made by this mapper do need to be undone, does anyone fancy having a go? It’d need to be someone with some experience of editing large relations, of course. If not I’m sure that we (the DWG) can, but we being non-local to Alaska/Canada there may be things (like the node and way edits) that we’re unfamiliar with.
I’ll also mention this on talk-ca, talk-us and OSM-US Slack, but it made sense to try and have the discussion in one place to which everyone has access.