Your system asks for reduced motion, so VFX-JS draws nothing. Demos on this site show plain HTML.
Type
TransitionUniforms
vfx-js/src/transition/types.ts:10 ↗import type { TransitionUniforms } from "@vfx-js/core";Numbers, vectors and arrays; no textures.
type TransitionUniforms = Record<string, Exclude<EffectUniformValue, EffectTexture | EffectRenderTarget>>