They also started rendering and preserving Unix-style line endings (LF).
Very welcome breaking changes :)
The inclusion of autocorrect (that I mentioned) would be example here: previously, it would accept whatever text you gave it verbatim. Now, it will sometimes change non-dictionary strings to dictionary words.
(Another thing that bothered me was that, on the update, it forgot my font settings and I had to work to re-find them.)
I'm happy to admit my phrasing was confusing, but not enough so that you would be unable to see the relevant failure mode.
Notepad addresses a specific use case (dumb text editor). If you have a different use case, there are other applications that handle it.