ParamSerializer for onRequest (interceptor) destructing string (ufo.withQuery)

As Axios does have the paramsSerializer I wanted to recreate this behaviour in combination with qs.
To achieve this I've created an $fetch instance:

export const apiConfig = {
    baseURL: 'https://jsonplaceholder.typicode.com',
    onRequest: ({ options }) => {
        options.params = qs.stringify(options.params, { arrayFormat: 'comma', encode: false  })
    }
}

The request params:

sortBy: "test",
test: {
    foo: "bar",
    arr: [1, 2, 3],
}

After stringify options.params results in:

sortBy=test&test[foo]=bar&test[arr]=1,2,3

The request by ohmyfetch:

https://jsonplaceholder.typicode.com/todos?0=s&1=o&2=r&3=t&4=B&5=y&6==&7=t&8=e&9=s&10=t&11=%26&12=t&13=e&14=s&15=t&16=[&17=f&18=o&19=o&20=]&21==&22=b&23=a&24=r&25=%26&26=t&27=e&28=s&29=t&30=[&31=a&32=r&33=r&34=]&35==&36=1&37=,&38=2&39=,&40=3

As you can see the params are getting destructed by withQuery
https://github.com/unjs/ohmyfetch/blob/main/src/fetch.ts#L109

This issue is similar to: https://github.com/unjs/ohmyfetch/issues/117

Start at the withQuery call in src/fetch.ts around line 109, using the reported onRequest example and serialized string as the reproduction. Verify why the string is treated as iterable query input, then ensure the request URL preserves the serialized parameter string and confirm it with a regression test.