For both functions and properties. Effective java tells us "make all private as possible", and kotlin design is about glance. Closest example where its done: default final classes.
I found myself distracted by this in my classes:
private val private val private var private var private var private var private val
It seems natural to private "all the things", and then open only necessary ones.
I believe you discussed this before(didn’t found anything in this forums tho), and i just need to calm myself with reasons why it is done this way.