I upgraded both the Qt plugin to 2.7.1 and VS 2019 to 16.11.2 at the same time. Immediately afterward my main project, that I've been working on for months, started locking up the VS UI as soon as I opened the solution. If I uninstall the Qt plugin it opens fine, but obviously I can't build. I tried upgrading to the 2.7.2 pre-release QVST and that allows me to open the project but occasionally it'll still hang VS, usually at the end of a build or when I'm launching a debug session. I've tried letting it sit for 20+ minutes and it never recovers. Once it hangs like this all I can do is kill it from the Task Manager.
Full disclosure my project is HUGE. It's a solution with over 100 separate EXEs/DLLs and literally millions of lines of code. It's also a mix of MFC and Qt using QtWinMigrate. So this may not be something that's easy to replicate. I tried another small Qt project I have and it seems to work fine, even with the older version of the plugin. Only my big project has issues.
If there is some sort of log or addition info I can provide let me know.