Bug Videoplayer show the wrong frame

I'm making a plug-in for playing volumetric videos, using videoplayer to decode textures, get the current texture in frameDeady, and match the corresponding mesh to generate the model, but sometimes the videoplayer cannot return the correct texture. For example, my video There are 85 frames. When I finished playing the second time, the 0th frame texture given to me by the videoplayer was actually the 70th frame, and every subsequent frame was correct,this problem does not appear every time, the probability is about 10%,is this a known bug in Unity?

 

The preview function I developed in the editor mode also encountered this problem. The last 2 frames of texture given to me by the videoplayer are actually the 0th frame.

 

need help plz