I hope she will be OK @user89066511 But yeah, saying shit like on social media is frowned upon massively. As has been said, people have been sacked for less. In my experience, the employee is more likely to be sacked for something like this, if they are not hugely popular with the employer (maybe flakey/bad timekeeping/bit lazy,) and it's a good excuse to get rid.
I know someone who (nearly 2 years ago,) posted a photo of his cat sitting on the toilet in the bathroom (the lid was down, but he just thought it looked funny.) He worked for a certain chain of hotels, and at the side of the cat was a small towel rail, with a towel hanging off it. A towel that he had taken (stolen) from the hotel.
The photo was copied by someone, (he never discovered who,) and sent on to the hotel manager. He was sacked for theft. A single towel that would have cost less than a fiver to buy, and he stole it and took it home, and it cost him his job. He was 57, and had been in the job for 25 years. I think it cost him his works pension too.
He has no skills or qualifications, and he is in his late 50s. That, combined with the Covid pandemic (which started just 3 months after he was sacked,) means he is still unemployed, nearly 2 years on.
As I say, be VERY careful what you put on social media!