Rescinded offers are an extremely rare occurrence. If I had not one, but two offers rescinded I'd start wondering if maybe employers were discovering something they didn't like during routine background checks: Unflattering social media posts, something on your record, and so on.
Maybe it's purely coincidence, but if this becomes a pattern I'd start looking more closely for potential issues in your public profile or public records.
If Amazon gives me an exploding offer, I shed no tears for Bezos by rescinding. You might perceive this as rare depending on where in your career you are, but going through this has fundamentally changed my perspective on job hunting.
There is a power imbalance. If I rescind, a normal company will survive. When I was rescinded on, I had to completely change my life plan, apply for unemployment (unsuccessfully), and re-interview while studying for finals. In a twist of irony, I ended up rejoining the company that rescinded my offer a year later (it's a good gig, what can I say) and it spread that some interns had their offers rescinded that year -- bloodboiling. Companies will literally not care, and I will not either.