To focus better on our core product, we occasionally have to discontinue features. For R23 Maxon has removed Virtual Walkthrough, the Sound System (Microphones and Loudspeaker objects) and ProRender from the product package.
There is still good news for ProRender users though:
Going forward, Maxon is transitioning updates for ProRender to AMD, who are committed to continued support for Cinema 4D users. In 2021, AMD will update the ProRender integration to the next-generation 2.0 standard, bringing its benefits to Cinema 4D workflows including an improved rendering algorithm, accelerated CPU + GPU performance, Full Spectrum Rendering, USD support, and more.