There was what I now know is just a bunch of burned on shit on the bottom of the pan, my aunt swore that was the patina from the seasoning and I had to let it build, this was years ago. So yeah, she's wrong and I was dumb to listen to her. When burned shit starts to stick/be left on a cast iron skillet it kind of forms a flat mound of carbon in the middle of the pan that just compounds over time, but it's all crackly like the video talked about with certain fats. So I had to scrape it, then get some horrifying chemical to put on it, then scrape some more, etc. Basically I had to take it all the way down to bare metal and reseason.
But if anyone was on the fence about cast iron, my experience isn't typical, I listened to a dumb person. Now I just do the same thing TJT does and it's simple and it works and I never have to worry about it.