This leaves "full stack JS" in an awkward middle ground. Sure, you could still use it on your backend (like PHP), but why?
We use JS because there were literally no other practical options, but better browsers and WASM are providing new options.
If I were starting a new company today I would certainly seriously consider Java or Kotlin instead.
Only you'll get higher-level abstractions (pattern matching, FP-style maps/flatMaps&Co throughout the standard library) and powerful collections with full support for generics.
Better yet, start with Kotlin from day one.
If you are looking for all the advanced type system features, kotlin is definitely not going to put you in the same spot, but if you are hiring Java devs, training them is a far easier lift: They can mostly train themselves.
I'd hope that after another version or two of scala3, when more organizations are happy running it in production, we might have an easier onboarding road, where we don't have to explain implicit parameters, implicit conversions and implicit classes, just so that we can get to the real meat that is the mechanics of type classes. But, as is, there's good defensible reasons for many teams to go try Kotlin first.
Personally I would never trust JavaScript on backend.