Building is completely broken after upgrading to Windows 20H2

When I open existing qbs project or create a new one (Qt Console App), qbs.exe hogs all memory and terminates after a couple of minutes. Build commands are not available. See screenshots qbs1,2,3.

I've also tried to create a new project of the same kind with qmake build system. Qt Creator hangs in "Reloading Project" forever.

I've seen this issue with QBS for the first time about a month ago, right after the first upgrade to Windows 20H2. I was short in time and simply downgraded windows to previous version. The problem was gone. Now 20H2 is back again, thanks to auto-updates. I'm ready to help in diagnostics until I haven't downgraded it one more time...