Reddis Stack JSON: Nested JSON vs namespace usage recommendation

Question

The redisinsight workbench use namespaces to store JSON objects, such as:

school_json:1 -> {...}
school_json:2 -> {...}
...

But I am asking myself if that is the way to go when dealing with JSON documents. The JSON examples at https://redis.io/docs/stack/json/path/ showcase how to store items in a nested JSON object called store.

In my case I would like to store users. At first I had a structure where a toplevel key users exists such as

users -> {
    1: {                        // actually I'm using a uuid here
        username: "Peter"
        email: ...              // etc.
    },
    2: {
        username: "Marie",
        email: ...
    }
}

Or should I use namespaces here as well which would look somewhat like:

users:1 -> {
            username: "Peter"
            email: ...
        },
users:2 -> {
            username: "Marie",
            email: ...
        }

I assume that using namespaces would have performance benefits over nested JSON but the example in the redis documentation which uses a nested JSON object to store several items confused me if that is actually true.

I found this answer but that is discussing redis, not redis stack using JSON (which may come with other optimizations).

Thanks in advance!