While I can’t fully confirm this as I don’t have the necessary knowledge to review the source code, Intel’s implementation write-up specifically mentions doing work on this front and implementing DD for H265.
We also added support for the dependency descriptor RTP extension for H.265/HEVC, originally designed for AV1. This extension conveys the reference structure of frames at the session layer to media servers and receiving clients, enabling precise selective forwarding of video frames based on whether the current frame’s dependencies have already been forwarded.