Varying results about which compiler and C# language version is in use?

Question

I'm using .Net Framework 4.7.2 and am testing setting a solution of 11 projects to use C# 11 syntax.

If I use Directory.Build.props with the following content in an aim to set the entire solution to utilise C# 11 syntax:

<Project>
 <PropertyGroup>
   <LangVersion>11</LangVersion>
 </PropertyGroup>
</Project>

If I then use #error version in the code behind files.

Upon attempted compilation (which does result in an error) I get two differing results; in VS2022 Pro error tab window I get:

Error   CS8304  Compiler version: '4.6.0-3.23329.3 (5db00029)'. Language version: 7.3.  

For the same compilation run, if I then look at the VS 2022 Pro output tab window I get:

error CS8304: Compiler version: '4.6.0-3.23329.3 (5db00029)'. Language version: 11.0.

Why does it say C# 7.3? Why the difference? I know that for .Net Framework 4.7.2 the default (if isn't specified) is 4.7.2, but when i have explicitly set the entire solution to use C# 11, why is it reporting C# 7.3 ?

P.S. When it's set to use C# 11 and reports C# 7.3 and C# 11 as described, I can use C# 9 syntax such as target-typed object creation, and it will compile and run without issue... so again, why say C# 7.3 ?