Remove Perl6 from the set of built-in languages. Perl6 was renamed to "Raku" in 2019, so the current display name is wrong. Further, the syntax highlighting is outdated relative to the latest text-mate grammars. Removing Perl6 entirely would reduce this maintenance burden, and allow extension developers to iterate independently. There are many languages far more popular than Raku that require extensions to define the language configuration and syntax highlighting (e.g. Scala, Kotlin, COBOL, Fortran, Haskell, Erlang, Lisp, Scheme).

If Perl6 is removed, then vscode would automatically prompt users to download the extension for Raku, which provides updated syntax highlighting and a language server. https://github.com/bscan/RakuNavigator

Example of incorrect syntax highlighting can be seen here where a user was using the old built-in "Perl6" highlighting instead of the updated Raku highlighting. bscan/RakuNavigator#1

GitHub's highlighting has also already shifted from using the old Perl6 grammars to using the newer Raku grammars as can be seen here: https://github.com/github/linguist/blob/master/vendor/README.md

Thanks!