Right, so first and foremost those are really quite poor results unfortunately, in terms of frame rates. That said, it’s an AMD GPU which struggle with OpenGL games in Windows, so perhaps not unsurprising. Added to that, the performance on Makuri Islands is pants, so it could be due to that anyway. Don’t get me started…
That aside, there’s another recent discussion where people with AMD cards are getting crashes in the same spots all the time in Watopia. So there’s a reasonable chance it’s just this same problem. Here’s the thread: [October 2021] Zwift crashes with new AMD display drivers
Another potential cause is if you have any overclocks on either your CPU or GPU. Zwift is really good at causing crashes on an overclocked system, even if you’re stable in every stress testing program and other games etc. So if you have any, back them off or remove them altogther and see if that makes any difference.