Hello there, I'm the maintainer for Anki, which is soon to release version 2.1.0. It depends on Qt5, but they have decided to depend specifically on version 5.9.x, because that is a long-term support release of Qt. (See the start of http://doc.qt.io/qt-5/whatsnew59.html for example.)
Debian doesn't support 5.9 any longer, so do you have any suggestions? I could remove the code which checks the version of Qt5, and just ensure that it's greater than 5.11 (because apparently there was a bug in Qt 5.10 which has been fixed in 5.11), or I could wait for the next LTS version of Qt5 to appear, or I could just leave the Anki package uninstallable for the time being. Best wishes, Julian