Separate encode problems from host problems
Not animating, not moving, not playing
Confirm the file loops locally first. Some CMS themes use background-image tricks that freeze GIF. Try MP4 on those hosts (see the format comparison). A loop that “isn’t moving” in-studio is often a single frame, a delay so high it feels static, or stills that never made it onto the timeline.
Quality loss, blur, pixels, wrong colors
Over-downscale and a low quality slider look blurry. Pixelation is usually a tiny source stretched toward ~1200px. Wrong colors are palette banding — flatten gradients, raise quality, fewer unique hues. Photographic skies will posterize; that is the format, not a corrupt file.
Upload errors, speed, and loop seams
Won’t upload / not supported / upload error: shrink via target size and the website spoke’s budgets. Too slow or too fast: change delay. Looping problem: infinite versus counted, plus the last-to-first seam. “Repair” means re-encode from frames or video, not a shady binary fixer.