Android App - No umlauts in textviewer

I use the android app 1.4.3. When I open a simple text file (.txt), the built-in textviewer does not show any umlauts. I save my passwords in it. It would be great if it could do this in the future.

Is this reproducible on your setting? If so, can you please describe in more detail what you do and how I can reproduce this?
Because on my device I can create .txt files with umlauts without any problems. Opening them on my Ubuntu machine and also creating one using my desktop and opening on the phone works like expected.

I have now created a text file with umlauts on Windows 10 with the standard notepad editor and there it worked in the Android app.

With the password file it is a text file that is encrypted and decrypted with AxCrypt. It seems to create the text file with a different display code after decryption in the Cryptomator Safe. On Windows this is displayed normally and in the Android app the umlauts are lost.
I now copy the contents to another file, then everything is displayed correctly in the Android app.

Thanks for asking in detail.