QString msg = "BUG Reporting:<a href='https://github.com/xuronghua2001/xxx/issues'>Github</a><br>Update:<a href='https://download.csdn.net/download/duckSoup_2001/xxx'>CSDN</a><br>E-mail:xuronghua2001@outlook.com" ;
QMessageBox::about(nullptr,"关于",msg);

参考Python QMessageBox new line '\n' and link broken - Stack Overflow