The colored dot in front of the user avatar is a quick availability indicator based on the event time. A green dot indicates a full 100% availability, red indicates 0% availability and yellow means the user is partially available, which corresponds to a value anywhere between 100% and 0%.
If the user has any conflicts if they were to be assigned to this event, a conflict icon will show behind their name. A blue icon indicates a soft conflict like the user already having an event on that same day. A red icon indicates a hard conflict, which for example could mean the user is contractually not available that day.