You are trying to change specialty- there is almost 0 chance a swap will work. You are also very late into 2021 match season, and likely won’t get a single interview applying this late.
Your most plausible options are as follows.
1. SOAP into a program in March. I dont know what the exact rules are. You need to find out whether you are SOAP eligible. This match season is an uncharted territory and no one knows how the match will play out. There may be some solid programs that go unfilled. If you were a competitive IM applicant, this is probably your best bet.
2. if you cant find a position through SOAP, applying in 2021-2022 means you will start CA-1 year after your PGY-2 medicine year at the earliest. I dont know why you want to switch out, but if you are doing 2 years of IM, you might as well finish it, which will make you a more competitive applicant for Anesthesia when you apply.
3. Apply to IM fellowship that gives you what you are looking for in Anesthesiology. You are already through the intern year, and most likely, you will have to finish up to pgy-2 IM anyways. Why not just apply to IM fellowships at the end of pgy-2? Some food for thought.
#1 and #3 assume that you are a competitive applicant to compete against unmatched surgical subspecialty applicants for SOAP positions and are at a solid tier IM program where you won’t have difficulty matching into IM fellowships. If you are not, #2 would be your best bet.