The workaround I find is to use latest version of Mingw64 (G++ -v : 9.2.0) when I want ico instead of mingw toolchain built with Upp.
I still got a version of Upp (v11873)(G++ -v : 7.1.0) with working toolchain, If you want I can give you some information about version of all exe from mingw/bin
Best regard
No need. I know that the problem is between windres and lld.
So currently the choice is between very slow linking times and working icon and fast linking times with icon.
Perhaps I will find a way how to activate original slow linker just for release mode...