How to animate css gradient in svg?

Question

css

It is necessary to make the effect of the flowing text, i.e. as in the rectangle in the example, except for the gradient, I did not figure out how to do it, but the problem is that the transition does not work on linear-gradient, keyframes also does not animate with a gradient, I decided to use SVG animation, but if you just write the gradient values ​​there then it doesn't work, how to implement it?
https://jsfiddle.net/morskaya_ulitochka/1k7bjwzs/17/

Answer 1

So ?

Answer 2

js