This is... interesting. After adding the capacity for users to limit who can reply to their tweets last August, Twitter is now extending the same to promoted tweets, so that brands can limit who is able to reply to their ads. We’re making it easier for brands to control the conversations they start on Twitter. Introducing Conversation Settings for Ads:— Twitter Business (@TwitterBusiness) March 9, 2021 As you can see here, now, within the Twitter ads creation flow, you'll have the option to choose who can replay to your promoted tweet via a new dropdown menu. As with Twitter's regular conversation controls, advertisers will be able to leave it as the default, which will mean that anyone can reply, or they'll be able to select “People you follow” or “Only people you mention”, restricting who can respond.