I too had a hard crash 15 km into the Turf N Surf route. However the companion app did manage to record the ride up to the crash.
I’m using an iMac (Retina 5K, 27-inch, Late 2014), running the latest version of Big Sur (11.7.1). Big Sur is the last version of macOS that is supported on this Mac.
One detail is that I was taking a photo with the Companion app immediately before it crashed.
BTW, this is the first time Zwift has crashed on me. I’ve been on Zwift (using this computer) for over a year.