Newmark interview questions

At the end of January 2020, the hiring manager for this company reached out to me on LinkedIn. I replied, expressing my interest. My resume was submitted soon after. A few days later, I was called for an impromptu phone interview. The next day, I was invited via email to an in-person interview with three dates to choose from. They let me know what to expect and bring (planned runtime, design test details, etc.). Fast forward a week or so to the interview, and everything went as expected. Later that afternoon, they called me with an offer at $10,000 over my asking price, asking if I had any lingering questions before they got the ball rolling. I asked for clarification on three points: project ownership, project variety, and flexibility. They answered more or less satisfactorily, giving me a day to think it over and accept or decline by email or phone. I accepted the offer via email that night, asking if it would be acceptable to give my current employer the standard two week's notice out of respect to them (since they hadn't asked for a start date up to that point). They were moving along at a nice clip, so I fully expected to receive a formal offer letter the following morning. Nothing came by lunch, so I called, got their voicemail, and left a message. The minute I returned to my desk, an email arrived from them saying that, following our phone conversation, they had decided to go in a different direction and regretted to inform me that they were withdrawing their verbal offer. No further explanation given. I've never heard of that happening before. It's by far the rudest and most unprofessional thing I've ever experienced (not to mention the most unethical). Were they upset that I wanted to give my current employer sufficient notice? Did they not like my questions? Were they looking to hire cattle as opposed to thoughtful, intelligent people who don't take big decisions lightly regardless of the size of the carrot being dangled in front of them? However they interpreted our exchange, my acceptance of their offer should've told them that I had weighed the pros and cons and decided that I was willing to making any necessary compromises to work for them. I now see that that would've been a colossal mistake. If this is how they treat their applicants, I shudder to think how they treat their actual employees. I'd steer clear of this place if I were you.