>>384767605
Unity 2019 is the last version to support single-pass stereo rendering. From Unity 2020 onwards, Single-Pass Stereo Instanced is the only available option (other than Multipass which is hideously unperformant).
Because of this, shader authors need to update their shaders to support single-pass stereo instanced. Fortunately this is quite easy. However, this also means many older shaders like sunao will no longer work, and content you upload with sunao now will stop working when VRC upgrades to Unity 2020.