Favicon Problem. Don’t understand …

Choose “Is already in production” (second option) and then put in any version you like.
It could be a string literal or a integer.

Like my-fancy-new-version or 1.0.0

The important is that next time you update it, that value changes. This will “bust” the cache, it’s like when adding scripts or styles and you pass the version in the ?v= parameter.