

Well, my point is that it’s not considered a u, and Austrian and Swiss don’t use it.
Also, fun fact, some romance languages like French and Brazilian Portuguese have an identical diacritic to umlaut but it’s different. It’s meant to mean the vowel is separate (like in the word naïve)
That’s exactly the other meaning I described. In Portuguese it was/is used to separate the vowels so they are not pronounced together.