Not happening on the desktop app (couldn't find an example). In Web-Player it only happens under <https://play.spotify.com/discover> (A). Under this link e.g. it showed me this the following album <https://play.spotify.com/album/6Ttnb4f8aPy7ytDJqV10FT> (B) and the title which should contain an "ü" in "Glück" wasn't visualized correctly in A. After clicking on it and getting to website B, the ü was visualized correctly. I tried logging out and back in (using facebook login) an and disabling addons (using private google chrome window).
FYI problem is still not fixed. Just to make sure that the issue is not on my side, I tested it in different web browser now too. Screenshot shows the problem with "Tiësto". Problem displaying Tiësto (image made in Safari, but e.g. in Chrome exactly the same)