Typing a name into This email is going to lists each group member once, including when a mailing list is already selected. A committee role sits next to their name when they hold one, and that label is omitted when it is the same as their name. Member, role and mailing-list suggestions do not show email addresses; saved external contacts still do.
When the site respects Head office marketing consent, people who have not given it appear in a separate group, and choosing them does not add a chip. Send to committee role addresses is offered when every person on the message holds a committee role. Adding a person to a whole-list send keeps that list as the Member audience, so Choose a list never sits empty. Committee people stay on Cc when you move them there from a chip.