Hi Weirdpictures,
I think it is written everywhere that M1 chip support is still considered experimental at this stage, and yes, it is still working under Rosetta 2 for plugins in Big Sur, at the moment.
PR11 is the first version supporting c4doctaneX with M1 chip in plugins, and you need to select the Cinema 4D.app, press Command+I, to get the Info panel, and enable the **Open using Rosetta** option:
The devs are still working with Apple on this... stay tuned.
ciao Beppe