Correcting someone’s grammar in an argument means you’ve run out of points.

Reaching for somebody’s grammar in the middle of a disagreement is a signal, and everyone in the room reads it. It says you could not answer the point, so you switched to a contest you were sure of winning. It also tells the other person their argument was strong enough to need a detour.

Notice when that urge shows up, because it usually arrives exactly when you are losing. Answer the strongest version of what they said instead, even if that means giving up a piece. Save the spelling notes for things being handed in.