Unwanted pixels appear in gifs



I have recently started using Aseprite for pixel art animation and I have two questions. I keep coming across this glitch where a bunch of unwanted pixels appear every time I send or upload my .gifs somewhere. The .gif works fine on the software, laptop and when I transfer it in my phone.

This pixels also appear when I convert my .gif into an .mp4 file.

I also downloaded the gif I uploaded and fixed the buggy frames in the that gif but it doesn’t work either.

This is how it appears when i convert or send it (with extra blue/red lines on left):

Same thing happened here as well over black and white screen:

The only way it at works fine is when i save all the frames as .png and then make a .gif.