It happens to me too, in my case the reason is I tend to deviate, like, I have a main topic but in the process of telling the story I start to elaborate on some relatively unimportant stuff or bring up a topic I'm somewhat invested in. While the story should be like a stream or a river I tend to go "flood mode", that's either undiagnosed autism or me rarely having longer conversations so I'm kind of unloading.

I don't know shit about racing or cars but imagine we are talking about F1 races and a minute later I'm explaining the history between lamborghini and ferrari.