Horrible interview experience with Meta

I interviewed a few months ago for a Machine Learning Engineer E6 position at Meta. I successfully completed all five coding interviews (including the phone screen), which I would classify as medium difficulty. The machine learning design interview was also straightforward. The overall process spanned over four months, marked by numerous reschedulings and cancellations without prior notification. Ultimately, the offer was for an E5 position, and no explanation was provided for the down-leveling. The recruiter was unable to provide a reason for this decision. I would advise against interviewing with Meta until their recruiting system improves. My previous experience with the company was positive, but the current process is significantly less efficient and professional.