TS and JS Grammar Extension version: 0.0.53 / latest
Code
const test = (foo, bar) => `${foo} ${bar}`
const test2 = (
foo,
bar
) => `${foo} ${bar}`
function test3(foo, bar) {
return `${foo} ${bar}`
}
function test4(
foo,
bar
) {
return `${foo} ${bar}`
}
(Interesting, seems as though GitHub does the same thing)
Screenshot:

Like the title says, if the arguments of an arrow function span multiple lines, they lose the proper argument syntax highlighting. The issue doesn't occur for regular functions. I've seen a few similar issues to this one, but most of them say something about the issue being fixed with #552. However, I'm seeing the problem even on the latest grammar.