Thanks for your response!
I am on VS 2019 Community 16.11.20. It's a brand new installation of VS2019. Previously I had VS2017 on that machine, uninstalled it, and installed the latest VS2019.
When I installed VS PHP, it required (I believe) ASP.net package addon. While downloading there was an issue, it seemed to have stopped. So I entered VS Installer. It showed an error with that package and recommended to "resume" the download, which it did, and seemed to have installed correctly.
After that I ran VS PHP installer again. This time it did not require ASP.net anymore, and just installed the plugin - showed no errors, all looked good. But when I rand VS2019 and opened the solution, that's the error that I got.
After this I tried to uninstall/reinstall VS PHP. That did not help. Then I tried to repair VS2019 through VS installer. That did no help resolving the issue either
Yes, PHP Tools Feedback is available in Help menu.