This is what has been happening to me. You can see a little spinning gear showing up in the bottom right and then freezing just before the CTD:
Both yesterday and today I had the same issue. Yesterday when there were connectivity issues and I was getting a CTD on the loading screen, same as OP, I had uninstalled my MSFS and re-installed. There was no benefit and eventually it was the servers/connectivity getting worked out which got me through the loading screen. I then installed all of my marketplace content and put the sim down for the night. When I came back in the morning, back to CTD on the loading screen. I went like that all day hoping that the connectivity would be resolved and I’d get through as I had the day before but that never happened. So about 2 hours ago I uninstalled again and started all of the installation over again. Suer enough just now it finished and I was able to get past the loading screen but now the Marketplace is unavailable. So either the re-install got me past the loading CTD or the fact that the marketplace was down got me past the loading screen CTD. I am betting on the latter and that my uninstall/reinstall didn’t effectively help despite appearances. So hopefully when the marketplace is back up, I can reinstall everything and get back and running but I’ve yet to be able to get into the sim with the SU11 update. I’ve never had any issues with prior updates or betas I’ve been a part of so hoping this is all server side anomalies that will get ironed out.