Watercolor Bleed lets pigment spread into the letterforms — soft edges, uneven density, the paper showing through where the wash runs thin. The irregularity is the effect.
feTurbulence generates a noise field and feDisplacementMap pushes the glyph edges along it, with feGaussianBlur softening the result — the same primitive chain a compositor would reach for. wc-bleed animates the spread so the pigment appears to travel outward rather than arriving pre-bled.
The bleed reads as watercolour because the underlying strokes already vary in width. On an even geometric face the displacement just looks like a blur.