There are many excuses I have heard over the years for chucking a sickie. Having a "mental health day" being about the worst of them. At least try and make it sound genuine: send the email or text at night so it appears you were up with something terrible; or send the email before your boss is up in the morning so there is no come back. Think of something that sounds realistic - fevers (no one wants you in the office post COVID 19!), a tummy bug, get creative with it. I can tell you that texting your boss at 7.32pm on a Sunday night, saying you have jet lag and can't come in tomorrow certainly sounds like an exotic and exciting excuse. Most people would be thinking "Wow! Have they flown in from Jo'Burg (it does sound more exciting said that way)/Sydney/Mumbai. What kind of life are they leading?" Under no circumstances when questioned where you have flown from name a domestic city with a one hour time difference. And at least have the courtesy not to tell me in the text you are comfortably at home at 7.32pm. That's just tiredness.
Excuses that need more work: 2 stars.