I know that sounds really weird. If you kill the ender dragon and then (in creative mode so it's easier) follow the center of its body until its final death point where it drops all of its experience while looking down at a pool (or one block) of water, then the water will not render for a second or two at that point.

I am attaching a screen recording as well as a screenshot of the screen recording where the rendering issue can be seen.

I tested this on lava as well but did not get the same results.

This does not occur in Fabulous! graphics mode, so it should be resolved as Won't Fix.