Unable to dynamically change the vertexColors inside useFrame

[eccentricdz]

I am trying to create a blinking effect on my Text geometry but the change in vertex colours inside useFrame does not reflect. Wondering if someone tried something similar and can help out.

Here is the code link:
https://codesandbox.io/s/react-three-fiber-playground-bgdgn?file=/src/App.js:1763-1796