The new Twitter Blue subscription service is constantly adding new features, and the latest ones have already been promised in the past. We're talking about Twitter Blue subscribers' tweets being prioritized in conversations, and allowing them to upload videos that are up to an hour long.
The longer videos are currently uploadable from the web, and they can be up to 1080p in resolution and 2GB in file size. Prior to this change, Twitter Blue subscribers were able to upload videos up to ten minutes long at 1080p resolution, with a file size limited to a 512MB maximum. For now, this limit still applies if you upload from Twitter's Android and iOS apps.
Regarding conversations, Twitter says users will see "a slight preference for replies from Blue verified accounts over other replies". In plain English - those who have a Blue subscription (or those who have been verified using the old system before Elon Musk took over) will have the topmost replies on any conversation.
Presumably, more features are coming to Twitter Blue in the future, to make it a more enticing proposition for people to decide to spend $8 per month (or $11 if subscribing from iOS) on the service. As of now, the blue verification badge is undoubtedly still the main draw - we'll have to wait and see how long that can still drive Twitter Blue subscription numbers up.