In a sense, there's nothing that mathematicians don't know about because numbers are a representation of how the universe works. (No, I'm not a mathematician, nor do I play one on TV, nor did I stay at a Holiday Inn last night)
My kid brother was trying to explain something about the pandemic to my sister a few weeks ago. After a few minutes, my sister, who has a masters in mathematics, said, "What part of this math do you think I don't understand?". I don't think she liked being talked down to.
Math was fun until they took the numbers away...