So you’re seeing it everywhere because that’s how algorithms work - once you click on one video, you’ll get hundreds more. Social media makes everything seem more common than it actually is. It puts you into a bubble where you feel like everyone is talking about it.
There are original mentions of twin flames from a long time ago and mentions in the Bible, but (as @Cassady said) most people have never heard of it unless they are going through it or come across those social media bubbles.
Back to your actual question. Similar to the one twin flame vs multiple debate, this is one of those things people disagree on. I think most of the community believe that it’s incredibly rare and less than 1% of souls or less will be here with a twin flame. Some believe everyone has a twin, but even then, think most will never meet in the 3D during this lifetime. There’s also a middle perspective that says it depends on your soul contract, meaning some souls planned this type of incarnation before birth and others didn’t.
What I’ve observed over the years in this community is that the answer matters less than people think. Whether everyone has one or not, what matters is whether you’re experiencing this connection and what you do with it.