My answer is purely anecdotal, but meat is very gastrically intense. I have never ventured beyond 20:4 IF and even then I avoid significant portions of red meat, even though I love it, purely to avoid gastric distress. It would not surprise me if the grilled steak was the culprit. If you need meat in your diet soon after refeeding I would suggest fish instead. Also, again anecdotally I would try to avoid a traditional “meal” and eat fruit and vegetables first, then starchy carbs, THEN meat. Kind of like a “warm up” for your stomach. As for why this was only an issue now upon breaking the fast early, I again can only rely on experience and say that maybe by ending early your mind had not reached a point where it decided to prime your stomach for eating yet, and as such was extra stressed by the sudden fat & red meat consumption.