What I hate about .NET is the atrocious naming.
Net Core, Net Framework, Net Common Core, .NET..
And God forbid any of these frameworks ever expose what they are in a config file. You start a project, hand it to a colleague and he can't figure out whether it's Framework or Core by looking at the files. You Google and are immediately bombarded by 15 year old threads.
Most web projects use JSON files for configuration. There are also some XML files for project configuration. If anything, you can run into too much configuration files.
If you start a project with .NET Framework in 2026, you're doing it wrong, plain and simple.
And the .csproj files do tell you which .NET they are.
<TargetFrameworkVersion>v4.</TargetFrameworkVersion> or <TargetFramework>net4</TargetFramework> is the old framework. Also, if the file is an unreadable mess listing all .cs files, it's generally .NET Framework.
<TargetFramework>netstandard2.0</TargetFramework> is .NET Standard 2.0, which means this library can be consumed from either Framework or modern .NET.
And finally, <TargetFramework>netX.0</TargetFramework> (X >= 5) is the modern .NET.