Certain unicode characters not rendered even though they are in font

Executing the program found in https://github.com/mumble-voip/qt_unicode_test/tree/master/src results in a result as shown here: https://github.com/mumble-voip/mumble/issues/4939#issuecomment-825856019

In short: The characters of the string "ᎭᎪᎢᎬᎭᎾᎷ" are not rendered, even though QFontMetrics claims that the characters are contained in the font.

When rendering this String in an UI, the String is rendered empty.

Note: The same text renders fine under Linux