GIFs don't seem to support progressive drawing of frames.

[gradha]

Running on an M1, downloaded ImageJ bundled with Zulu OpenJDK 13.0.6 and opened a GIF file:

Trying to play back the file inside ImageJ shows lots of dark pixels on the image. It seems like they represent the translucent pixels not updated on gif animations, and instead of being skipped, black is being used. Here's the output GIF image produced by ImageJ. Note how also the framerate has slowed down a lot.

I tried the browser version and got the same results.