I see these all the time. I think it is Android file based encryption. Entropy in such files also suggests encryption.
No one was able to point me anywhere, I asked several places, here's one: https://www.reddit.com/r/Smartphonefore ... ncryption/
and here: https://www.reddit.com/r/datarecovery/c ... ncryption/
In an Android developer forum suggested it was Android file based encryption. Without any further info to go on.
And it is my impression it was mostly Samsungs but that may simply be because it is a popular brand.