Wrong Umlauts + small letters in new hashtag bar (since v27)

[Der-K-2000]

Detailed description

I see at least two character issues with the new hashtag bar function below posts which will be introduced in version 27:

1. Umlauts and other allowed characters are converted incorrectly (e. g. Bäume → baume), although they should not be changed at all.
2. All characters are also shown in lower case, which is confusing for everyone, but especially problematic for accessibility reasons as soon as there are multiple words (like #AnDiesemTag).

Example:
https://ard.social/@tagesschau/113652054318347927

Web:

Tusky:

Steps to reproduce the problem

1. Write a post with a single hashtag line at the end.
2. Use Hashtags with Umlauts and in capital letters.

Debug information

Tusky v27 beta 1

[connyduck]

Thanks, we already fixed this #4802