Bitwarden because it has the "Teams" feature and can hsare passwords with multiple people. No sync issues like passing around a keypass file and worrying about having the latest version of it.
The people making this library aren't Scala refugees - they're a Scala shop that uses Kotlin on Android only, so they decided to bring over their idioms.
Kotlin is a much larger than Scala on syntax, has 100+ keywords and built-ins, compiles slower, all while having a way weaker OO system and and doing a small fraction of what Scala does.
I haven't made a formal study, but I think that it still ends up still being a smaller language. Scala doesn't have a lot of keywords, but it does have a lot of overloading of what those keywords do. It's something I have to spend quite a bit of time explaining when I'm bringing people up to speed on Scala.
The OO system is absolutely weaker. Depending on your situation, that can be a big advantage. I work in a mixed Java/Scala codebase, and, while I generally like Scala, one of our more annoying bits of yak-shaving is making sure outward-facing Scala code doesn't do anything to make itself overly awkward to consume from Java. I haven't worked as extensively in Kotlin, but, from what I've seen, you've got to spend a lot less time worrying about it there, because Kotlin stays much closer to Java's OO semantics.
My sense is, if type erasure or lack of parametric polymorphism are really causing you pain, yes, Scala is for you. Pattern matching, too. If your Java pain points are more prosaic than that, Kotlin is a less radical change that is likely to address most of them them without introducing too many new ones.