Resource attributes don't get merged with histogram record attributes?

[MidasLamb]

I create a resource like this:

const resource =new Resource({
    [SemanticResourceAttributes.SERVICE_NAME]: "MY_SERVICE",
    "otherkey": "otherval"
});

const meterProvider = new MeterProvider({
  resource: resource
});

and later on record something on an histogram:

latency_histogram.record(100, {"method": "GET"});

It is my understanding that the "otherkey" should get put on the labels of the histogram record, as they should get merged, but that's not the case it seems? The service name does propagate as I can see it in prometheus as the "exported job". If I comment out the SemanticResourceAttribute.SERVICE_NAME, I get unkown_service:node as the exported job.

Do I misunderstand that those properties of the resource should get merged in each of the individual metric records?