[2020] Screen Flash On Load - Asset Error?

Hmm, the fact that it runs fine with -noWorkshop but has the problem with -disableMods is unsual. I wonder if it's related to memory use, since assets causing issues like this is extremely rare (and I don't think I've ever heard of this particular issue caused by an asset).

How many assets are you subscribed to? If you have the Loading Screen Mod installed it will show you how many assets you have as it's loading.

I would definitely try to reduce the amount of assets significantly - either by unsubscribing or just disabling to test. 6000 assets take up around 64 GB of RAM. The free patch included some new assets, so it might simply have pushed you over what your system was able to handle well. If you got the DLC as well, you should expect to remove 3-400 assets to get down to the amount you were at before.