Meaning
The slightly smiling face flipped upside down. That small twist turns a polite smile into something ironic: it often signals sarcasm, silliness, or the strained cheerfulness of someone trying to stay positive while things go wrong.
A classic use is commenting on your own bad luck: “Missed the bus by ten seconds, and now it’s raining 🙃” It can also mark a joke as a joke. Because the tone is layered, it may confuse people who take emoji literally, and in a genuine complaint to a colleague it can look flippant.