Temporal Delimiter OBUs are being inserted before every frame
Created by: jamrial
TD OBUs are meant to be present at the beginning of a Temporal Unit, precisely to delimit them, and not before every frame, showable or not, within a given Temporal Unit. All these extra TDs are pointless overhead in the bitstream.
A simple "rav1e INPUT.y4m --output OUTPUT.ivf" seems to be enough to reproduce this. In my tests i used https://0x0.st/sfRh.y4m.