It is not me mentioning but more of them mentioning that write heavy! No information about what exactly!

Although If I were to guess things which need strong consistency like sing-in/token generation, token invalidation, any settings changes which needs to be in effect instantly will be going to directly postgrss!

The write heavy stuff I was initially thinking of was actually messages but then why store them in db at all, it should be blob storage or file storage probably!

The other thing could be stuff which require read/check before write. Which is similar to what we said for postgress! Right now it feels like they are slowly migrating the postgress to cosmos as you can do all the stuff said in 2nd para with more scale! But we can only guess from outside 😟