"Must of" isn't a thing, and you should understand that without someone pointing it out. Same as "could/should/would of" isn't correct. Learn basic grammar.

[–] [email protected] 18 points 11 months ago

You're being unnecessarily rude, and you should understand that without someone pointing it out. Learn basic manners.

[–] [email protected] 1 points 11 months ago* (last edited 11 months ago)

Yeah. You're a bit direct but I do need a person like you to point things up for something I did wrong unintentionally.

However I wonder if any native speaker don't realize there's something wrong with these sentences. Even a non-native like me can see that. Maybe it's intentionally done; they know it's not correct but they just want to keep up with the wrong trend.