SVG blur by mask, how to do it?

Question

SVG

There is svg, you need to apply the blur filter to make it look like in the picture. Tell me how to do this or at least in which direction to look. I broke my head in search of a solution (
An important point: it is svg masks / filters for svg that are of interest.
Abstract code:

<svg>
  <defs>
    .... ???
  </defs>
  <g>
    <path d="..."/>
    <path d="..."/>
    <path d="..."/>
  </g>
</svg>

Answer 1

at least in which direction to look?

Look towards creating two layers with the same content. The top one is blurred and masked from the gradient. And then you need to play with the parameters until the desired result is achieved.
It is possible in the opposite direction - blur the bottom one, and apply a mask to the top one, only of opposite colors.