Do you share the videos that make you laugh on TikTok or do you just swipe past them? Because that's part of the key. TikTok's algorithm is definitely way more aggressive than Instagram's, but I think people exaggerate a bit when they say that's all it is. Instagram also has a pretty personalized algorithm, the thing is that the format interrupts the rhythm of the humor.
On TikTok the joke lands in 5-15 seconds with no interruptions, while Instagram shows you 3-4 videos in a carousel, so by the time something funny happens you're already thinking about swiping to the next one. Plus, TikTok has a culture of "disposable" videos where people experiment way more with absurd formats, weird transitions, jokes that are super specific to the internet. Instagram is still more formal, even in the Reels feed. TikTok creators feel like they can do things that on Instagram they'd feel don't fit 😅
What I notice is that both platforms show you what they want you to see, but TikTok nailed the formula of "the more you watch, the more I know your sense of humor" and that's rare to pull off. Instagram still filters a lot by global trends and who you follow, but TikTok doesn't care if you don't follow anyone, it shows it to you anyway. So yeah, it's the algorithm, but it's also that TikTok's format was literally designed for humor to work better.