8x was overkill, and 4x is a tad unstable especially with 1.16.1 with texture allocation issues. Current pack settings will be reset back to 100% size due to preset naming changes.
Since it's not possible to update 300+ shaders manually and automation was possible, I thought that I'd take the honor and create a script that's able to automatically convert all of the shaders to be cross-compatible with Vulkan. And change the graphic pack versions to version 4 of course.
Also, the script has some nifty testing code which compiled every shader as OpenGL and Vulkan, but for that see the details that I've written below.
**Here's the script that I've made to do all of this. No manual edits were needed:**
https://gist.github.com/Crementif/8d98a855b95f219d95298fb3db99deae