deepin I can confirm this. I use the german keyboard and can't use "@" in web browser and no german letters like "ä, ö, ü, ß" in password-fields.
It works in all other Apps though.
deepin For now, I have found a solution:
Every time I restart my computer, I have to change the keyboard layout for Polish characters to work. Sometimes they work in the browser when I have the “Polish” layout set, and sometimes when I have “Polish (British keyboard)” set, and there is no algorithm for when Polish characters work on which layout.
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Clean installation of the system and Polish language selected. The keyboard shown is Polish. However, it is not possible to type Polish characters, e.g. alt+a.
Polish characters can be typed normally in a text editor, but unfortunately not in a web browser.