I know someone who has a habit of correcting other people if they make a grammatical mistake or use a wrong word when they are talking.
Queenie, aren’t they being very rude? And should I say something about it?—Offended
If they are doing this in public when the other person is talking, yes, it is very rude.
To avoid being rude yourself, talk to them about it – tactfully! – in private, and hope they listen to what you have to say (without correcting any mistakes you may make, I hope!).