The above are 1-second window captures of one of the more poorly transferred 4k films: Pirates of the Caribbean. As can be seen at about the 130 minute mark, the video bitrate alone (not including audio) jumps to about 110Mpbs. Note this film does not contain the DV metadata layer as it's only HDR10; this usually adds about 10-15% in file size and thus bitrate as well. In this case, you are correct that the bitrate generally sites below 90Mpbs. But that's not accounting for audio, subtitles and DV metadata. Yes those are relatively small in size, but it eventually all adds up and can easily push the total bitrate above 100Mbps.