A "small potatoes" rant for sure...
We use Microsoft Teams here at work, but this of course applies to any instant messaging system. It drives me crazy when people message me with:
"Hi."
or
"Good morning."
And then wait for me to respond before telling me what it is that they need.
Just tell me what you need with your first message! Now I have to respond and feel like I have to sit there and wait for you to get back to me.
It never really bothered me much until McNulty made a similar post about texting some time ago and now it drives me crazy.