Just the built in Windows stuff. As above, it’s now stable on 1903 (bar the irritating flickering) and was previously stable on 1809 with an AMD card. The game, Windows and my Nvidia drivers are all the latest versions.
I’ve been on google a lot trying to troubleshoot this and constant CTD seems a fairly widespread problem over a long period of time for a small proportion of users. There doesn’t seem any link between the systems affected although I haven’t seen any problems from people with AMD cards. As usual with this kind of thing none of the solutions suggested across various forums actually work!