I actually buy that this probably happened. In any event, there's really no use in playing the "is this fake" game, so we may as well just take at face value that what the OP said is what happened.
That said, there isn't a ton to be done here other than explain yourself and apologize profusely. To directly answer your question, yes, of course you can get in trouble for sending this email. You can get in trouble at any time for saying bad things about your program. But also, both you and your program are locked into starting next year together by the match agreement, so they're stuck with you for at least 45 days. They almost certainly don't want to go down a resident. You almost certainly don't want to become unemployed. So I'd probably follow up your original email with the shortest version possible explaining what happened as you did here, and ask to discuss further directly by phone or Zoom. If you present this error as born out of negative emotions from matching lower than you had hoped, but that you remain excited about the field and want to learn as much as possible from their program, these are the sorts of emotions people have to sort through all the times after the match. Most people don't open their mouths (or an email) and give voice to these feelings, but if you are honest and transparent I suspect that you will be able to move forward from here.
You should absolutely be a model resident once you start, be the person who shows up early and complains the least, etc. If you run into any problems after starting at your advanced program, this negative first impression of you is the sort of thing that could get you some unwanted scrutiny if you struggle or appear to be unhappy.