Writing Einäscherung the bug recreates- thats because the ä appears to be constructed using two separate characters: a plain lowercase 'a' followed by a combining diaeresis (¨). This is called a decomposed form, where the umlaut is not part of the 'a' character but is added separately. Writing Einäscherung the bug doesn't reproduce- thats because the ä is written using a single character, which is the typical way to write it in German. This character is a lowercase letter 'a' with an umlaut (two dots above it). safari has specific rendering issues with combining diacritical marks, especially when these marks are handled differently in the rendering engine compared to precomposed characters.