The screen shows that someone is typing, but cannot show what they are struggling to say.

The typing indicator tells you that something is being composed and nothing about what it is costing. Someone may be writing and deleting for ten minutes trying to find a way to say something hard. All you see is a signal that appears and disappears, and the interpretation is entirely yours to invent.

Give people time before reading anything into a pause. If something important is being discussed, consider moving to a call or a conversation in person, since the medium is stripping out exactly the information that would let you understand what is actually happening.