I have an MSI 3080 10G LHR, an AMD Ryzen 9 3900X 12-Core Processor, and 32 Gigs of RAM, yet I get these black shadows inside certain folds of fabric. I have seen it on flags, this umbrella, and certain clothing pieces. I have GeForce Experience set everything to Ultra/Psycho settings and the fps runs at 62 on average with a dip here and there. Any idea what may be the problem? What can I adjust to fix this?

It's a rendering problem. Got nothing to do with your hardware, it's an issue where the game engine is unable to properly create the lighting effects on objects.

Ironically, the higher the graphics settings, the more likely it is for something like that to occur.

Reducing the light reflection settings will make things more blurry overall, but should remedy that issue.