Manhattan Bridge Orthodontics interview questions

The manager who interviewed me is very nice and with good attitude. I went in for an hour long interview away and I got a call the next day offering me the job, which I happily accepted. But just a week before I was to start, she informed me that they decided to give another candidate the job because they don’t think they can offer me my desired salary in the long term, which I found unprofessional because I informed them my desired salary and was willing to accept the training period salary during the interview. But at the end, I got rejected because of this reason is kind of confusing and seems like a red flag. To anyone applying for a job with this company be aware.