The requirements for Building Qt 6.2 for Device Creation using yocto just calls out to meet the requirements of yocto. However 6.2 apparently requires GCC8 or newer which is not a requirement of Yocto, and GCC7.5 which is standard issue for Ubuntu 18 (which I suspect is common). Claims to be C++17 compliant so there's no online documentation driving this requirement.
It would be great if there was a note add this page:
Stating that your build environment must have/use GCC 8 or newer.
I only learned this by finding a related bug and getting an definitive answer by leaving a comment and getting response on