There’s no message button on my user card (?) - that thing appearing when the avatar is clicked. Because of that other users can’t start new conversations with me. So far I don’t know if it affects conversations started by me. It’s the first time I know that a non-moderator tried to send me a message since November '18, and the first time since my username change including moderators.
Edit: If I send a message to someone they can normally reply.