From flutter/packages#7466 (comment):

"I think the next step is to file an issue to explore with the engine team whether making the copyPixelBuffer/textureFrameAvailable more explicit about call patterns (e.g., saying that calls will not be more frequent than ~the screen refresh rate) is something the engine team is comfortable with, so we know whether or not we need to build limiting logic at the plugin level."

In #7466 there is little issue that it assumes that copyPixelBuffer will not be called more often than screen refresh rate. It is not very critical for functionality but it would not be optimal if that did not hold. Current implementation holds this assumption but that is not documented.