noVNC uses unescape() in its javascript files to decode the page title. This does not work for special characters. Unescapt is marked deprecated in javascript, decodeURIComponent() should be used.
Fix for upcoming 0.7 release of noVNC: <https://github.com/novnc/noVNC/pull/817>
Fixed due to package upgrade from Debian buster Bug #35428. *** This bug has been marked as a duplicate of bug 35428 ***