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Correcting in public is almost always a dick move. Precisely because you don't know the circumstances:

1. They may be neurodivergent.
2. They may be facing a language barrier.
3. They may have been in a hurry and didn't pay attention.
4. They may suck at typing.
5. They may have been burned by their phone's autocorrect.
6. … and a cast of hundreds more.

Since you don't know, shutting the fuck up in public is the best thing. Ask if they mind correction, and if the answer is negative, correct them. IN PRIVATE.

The only time it's OK to correct people unsolicited in public is if they're being utter shits and acting as if they're smarter than everybody else. Then go after each and every error they make as an object lesson in why you don't act like an utter shit in a public space.