alt Hacker NewsThere are three possibilities though. One is Instagram copying TikTok, without their knowledge, the other is Instagram copying your TikTok feed with their knowledge but not their blessing, and finally Instagram copying your TikTok feed with TikTok's knowledge and their blessing. If we take a look at http://TikTok.com/robots.txt, it seems if you make your TikTok public, TikTok is happy to let Instagram take a look at it (but not a number of AI crawlers). What Instagram does with it is up to them, but it's in robots.txt.
The simplest explanation would be that Instagram crawled my TikTok's account's followers and is curating my Instagram reels based on that point in time.
However that's not what happened, because my "following list" is restricted to be viewable by "only me", even though my account was public. "Public" just means that you can view my videos without me accepting a follower request. And I don't have any videos anyway.
So I can only deduce that setting it to "public" flipped some bit in either Instagram or TikTok's backend to where now they both are sharing the same or very similar data to curate my feeds.