"You and I ."
Can we all just discuss how difficult it is to understand even what letters mean what without a romanized key? I don't know if this is an Android thing for the app or what. I can't just differentiate exactly which letter makes what sound and it makes things much more difficult to get into
This sentence says "you and I". You complained it corrected you to use feminine form even though you are a male. The only word that concerns you is the word "I" which is אני, which is used for both genders.
The only other option is if you meant "you" is about you. Again, אתה, which is masculine is the default answer and should not have been corrected to את which is feminine.
No, my answer was not supposed to be funny. So, help me understand what you actually meant. Because it's not clear.
As I already wrote, אתה, masculine you is the default answer, so I'm not sure how would they change it to feminine.
But more importantly, since you are doing the translating, you are the "I" part of the sentence, not the "you" part, so there is no issue.
Advice: don't take the sentences on Duolingo too literally. They are mixed up, switching between masculine and feminine and singular and plural, in order to help us exercise. If you take those too seriously, what will you do with the sentence אני פטרייה. (I am a mushroom)?