was turned away from a role because of the coding round during the final interview. There was a misunderstanding with the interviewer and that cost me the position, I can’t stop kicking myself over it

I finished the final interview for a Security Engineer role at a FAANG company. The last round was coding. I have a pretty good handle on scripting and I'd like to say I managed it overall but towards the end, I messed up on the last few lines cuz the interviewer tripped me up with something she said and I think there was a misunderstanding.

(Details if you care: During the last few lines, I wanted to use most_common() from Counter module in Pyrhon but while I was figuring out how to implement that in the context of the logic, she says "size". I understood this to be her telling me to use size function, but idk any size function in python, so I ask her what it returns and mentioned I've only used most_common function and she said length. I thought this was a function i hadnt heard of so I used it but i dont think it made sense. She probably meant len() but that didn't make sense to be next steps regardless?? And then she helped me with the last line of code by hinting what data structure to use. I think the last few lines of code were wrong and I should have just stuck it out with my initial thinking process by trying to use most_common function and finishing final steps from there). I'm kicking myself for not taking the time to look over what I wrote before moving on from coding UGH.

So anyways, that ultimately cost me the position. They did refer me to another engineering position though (not security engineering but I work with security, it's a different pay scale though and I'll have to work my way up through an internal transfer in the future). But damn, I'm so upset at myself. Any advice?