So you're saying the Blender developers made significant changes to the python API again after they initially changed it for the Blender 2.8 version for which the ProRender plugin was made along with tons of other addons made by others. That doesn't make any sense
Yeah, I traced the problem here: https://community.amd.com/thread/239567 some of the methods in the python interface started requiring a depsgraph object in addition to the main context object. Adding the code in the same way they modified the Cycles interface, I found the renderer works okay but the viewport no longer works. That issue follows the reports that have been seen since late April about issues with the viewport.
Nope, just a user with coding experience. I'm not sure if I'm going to be able to find the root cause for the viewport issues, but I may bisect released blender versions to see if I can find the last known good for the viewport issue.