Wow that was fast! Qt has acknowledged the mistake and have there own patch already in the system. Instead of swapping the "then" and "else" clauses they reinvert the "if" condition so it matches.
Either fix will work. So all we need now is to get someone from Ubuntu to add the official Qt patch to their Qt 5.12.8 version for Ubuntu 20.04 / Mint 20.04, Kubuntu,etc.
See:
https://codereview.qt-project.org/c/...omium/+/305139
for their official patch awaiting merge.
So if anyone has contacts at Ubuntu, Mint, etc, please point them at that official fix for Qt 5.12.8 and Qt 5.12.9