Tiktok is rolling out support for longer videos, up to 3 minutes.
The previous limitation was one minute videos, after initially starting with 15 second clips. Tiktok has been testing support for 3 minute clips since December but those were limited to select users. Over the coming weeks they'll be rolling out to all Tiktok users. The current 60 second format had since been copied by newer competitors, like Snapchat Spotlight and YouTube Shorts. Before expanding to 3 minutes, creators would work around by telling people to follow for part 2. It did help gain some followers but was annoying for viewers who had to scroll through creators' videos to find part 2 (or 3, 4...). Link