It may have something to do with the time of day you post, tags you use, or previous content you've posted. TikTok may be limiting the number of times it shows your videos. while showcasing your stuff to your followers is a sure way to get views, pulling in new viewers is the name of the game. If you post in the middle of the night. you are much less likely to find new viewers for new viewers for your content. Also, be mindful or the hashtags you are using when you make video description.