It depends on what content you watch on TikTok. Many comedy content creators on TikTok have identical, mirrored copies of their content on Instagram (an example is Leenda Dong, who has been very popular on both TikTok and Instagram).
This was also tested in practice in India, when the country banned TikTok in 2020. Rest of World published a report in 2023 with the conclusion that most users simply switched to Instagram Reels or YouTube Shorts without much complaint, just as the previous commenter predicted: https://restofworld.org/2023/america-india-tiktok-ban/