I agree that this information should be present somewhere, but a heading of "Your connection is not secure" is about as detailed as you can be for typical end-u

I agree that this information should be present somewhere, but a heading of "Your connection is not secure" is about as detailed as you can be for typical end-users. The extra information about why exactly it's not secure should be present somewhere, but for 99% of users these details are completely non-actionable.