When I send a message/warning to a user via flag icon -> “Send @user a message | I want to talk to this person directly and privately about their post.” -> Message / Warning the post gets lighter, almost faded out. This made me assume the post also got removed or deleted, but on reload I only see the “You sent a message to this user” under the post.
As staff, using the PM from there as a form of private moderation. Mostly positive, sometimes negative - and each time if anything changed with the post now that I sent a message or warning because visually something changed - until I reload.