BigSur 11.6.4 and Epson V850 Pro scanner

What I see is that drivers are available for MacOS 10.5 to Mac OS 11, once you select the correct MacOS, as this notice shows:

Attention: Your operating system may not be detected below. It's important that you manually select your OS in the Operating System drop-down menu below to ensure you're viewing only compatible files.

It appears that Epson has decided to not support newer macOS versions that 10.14 Mojave.

https://epson.com/Support/Scanners/Perfection-Series/Epson-Perfection-V850-Pro/s/SPT_B11B224201

You should contact Epson for any possible options they have.

See if Image Capture, included with macOS, will "see" the scanner and allow it to continue in service.

Scan images in Image Capture on Mac - Apple Support

Catalina, Big Sur and Monterey are all supported by the V850:

https://epson.com/Support/Scanners/Perfection-Series/Epson-Perfection-V850-Pro/s/SPT_B11B224201

Gary, Did you see this on that Epson page?: