Most 4k streams are 8-20 Mbps. A UHD runs at 128 Mbps.

Bitrate is only one variable in overall perceived quality. There are all sorts of tricks that can significantly reduce file size (and thus bitrate of a stream) without a perceptible loss of quality. And somewhat counterintuitively, the compression tricks work a lot better on higher resolution source video, which is why each quadrupling in pixels (doubling height and width) doesn’t quadruple file size.

The codec matters (h.264 vs h.265/HEVC vs VP9 vs AV1), and so do the settings actually used to encode. Netflix famously is willing to spend a lot more computational power on encoding, because they have a relatively small number of videos and many, many users watching the same videos. In contrast, YouTube and Facebook don’t even bother re-encoding into a more efficient codec like AV1 until a video gets enough views that they think they can make up the cost of additional processing with the savings of lower bandwidth.

Video encoding is a very complex topic, and simple bitrate comparisons only barely scratch the surface in perceived quality.