Why is there little rectangles when I export my animation as an MP4

Help
#1

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What Wick Editor Version are you using?
1.19.3

Describe the Problem
Whenever I try to export my animation as a gif or MP4, there are little rectangles.

What have you tried so far?
I have tried refreshing the page, but nothing worked. If this is supposed to happen, can someone explain why?

#2

May I see the animation?

#3

It’s deleted but you can try draw something yourself and export it as a gif and video and you’ll see what I mean

#4

mabye its the size of the canvas? i dont know a lot :P

#5

Tried changing canvas, doesn’t work.