As a fan of both Kotlin and Scala, I'd be interested in hearing if there was more to the decision to migrate away from Kotlin than their existing Scala code base.
I wasn't directly involved in this decision and I've never worked on our mobile apps, but I do work at Lucid. Almost the entire engineering team can write Scala. About 3 people can write Kotlin. That was a big part of it. The lead engineer on our Android app is also a Scala wizard.