I used paint.net and made a new picture with increasing hues about 15 times and I copied that to a new folder, renamed 1-15 to 15-30 and uploaded it to a gif website. I used cross fade
Try applying a background of #232323 to each frame.
Or
Select the text (outlined), shrink the selection by one pixel, invert the selection, and remove it.
Or
Don't use a website to make the gif, instead (if possible) save it as an animation.
I used paint.net and made a new picture with increasing hues about 15 times and I copied that to a new folder, renamed 1-15 to 15-30 and uploaded it to a gif website. I used cross fade
You could edit it on after effects, just edit the fuzziness. Or if you're just using it for this forum then just put the background of this forum on it.