Magento 2.4.5-p1: GraphQl unpredictable response

I have a strange issue on Magento 2.4.5-p1 on production (on dev I don’t get the issue)

When I send a request e.g.:

query {
storeConfig {
    store_code
    code
    locale
    secure_base_media_url
    store_name
    newsletter_enabled
}
}

I expect a response like:

{
"data": {
    "storeConfig": {
        "store_code": "default",
...

but in around 5 of 10 requests before the above block I get another bracket with the query like:

{
        "query": "query {n    storeConfig {n        store_coden        coden        localen        secure_base_media_urln        store_namen        newsletter_enabledn    }n}"
}{
        "data": {
            "storeConfig": {
                "store_code": "default",
...

So if I run the same request multiple times in a row sometimes the query bracket is there, sometimes not…
the content of “data” is btw in both cases the same

Does anyone have an idea what could cause this?

Thanks in advance!