Anyway, I hope the author can be a bit more specific about what actually has happened to those unlucky enough to have received these malicious updates. And perhaps a tool to e.g. do a checksum of all Notepad++ files, and compare them to the ones of a verified clean install of the user's installed version, would be a start? Though I would assume these malicious updates would be clever enough to rather have dropped and executed additional files, rather than doing something with the Notepad++ binaries themselves.
And I agree with another comment here. With all those spelling mistakes that notification kind of reads like it could have been written by a state-sponsored actor. Not to be (too) paranoid here, but can we be sure that this is the actual author, and that the new version isn't the malicious one?
Is this surprising? My model is that keeping with the new versions is generally more dangerous than sticking with an old version, unless that old version has specific known and exploitable vulnerabilities.