protected[this] was removed in scala 3[0]. And honestly, I can't think of a case where it was really useful.
[0]: https://docs.scala-lang.org/scala3/reference/dropped-feature...
[0]: https://docs.scala-lang.org/scala3/reference/dropped-feature...
It looks like the Scala project found allowing protected[this] fields as an escape hatch for variance to be unsound:
https://github.com/scala/bug/issues/7093
Going to have to chew on that and what it means for the same feature in Sorbet…
Thanks again for bringing this up!