play-scala-starter-example will not compile against Scala 3.3.6 in MS Code Metals

[umpint]

To reproduce I checked out this repo and went into play-scala-starter-example directory.
Changed scalaVersion to:
scalaVersion := "3.3.6"
in build.sbt

If I now run:
sbt run
The example compiles and runs fine.

But if I try to compile directly in Microsoft VS Code (using the Metals Extension) I get numerous errors like:

The import router.RoutesPrefix cannot be resolved

These errors are in the generated routes.java file that is generated.
I have similar issues with the files generated by twirl in another project.

Would you expect these examples to compile in VS Code Metals plugin when using scala 3.3.6?