Getting devices and tvs to play nice can be a pain for any given set - I don’t have a roku but comparing builtin YouTube/Netflix on a 4K hdr Sony oled with chrome cast and Apple TV they were all about the same with built in performing the best (optimized for the tv I presume) - apple tv with infuse using Emby as a library was best

Chrome cast is also greatly affected by what your casting with, VLC, Videostream, chrome can all produce very different results depending on the content