Maybe you're overthinking it. People just don't like to hear about something that's completely irrelevant to the conversation.
If you really care about improving some one grammar, send a private message. It can be very useful for a non-native speaker, especially if it's not a total stranger to you. Saying out loud "fix your grammar" doesn't make you a hero on a white house.
If you really care about improving some one grammar, send a private message. It can be very useful for a non-native speaker, especially if it's not a total stranger to you. Saying out loud "fix your grammar" doesn't make you a hero on a white house.