I just switched to a Windows 11 laptop (finally!) and had to setup everything again. In Visual Studio 2022 I was getting this IIS Express error "You connection is not private" error and the browser would not display my Web Site. The solution was to open Edge and type edge://flags (Chrome was chrome://flags), then find "Allow invalid certificates for resources loaded from localhost" and set it to Enabled.

I found the answer here: asp.net mvc - Your connection is not private NET::ERR_CERT_COMMON_NAME_INVALID - Stack Overflow