They look like this:

Metric #1
Descriptor:
     -> Name: http.server.duration
     -> Description: measures the duration of the inbound HTTP request
     -> Unit: ms
     -> DataType: Empty
Metric #2
Descriptor:
     -> Name: http.server.response.size
     -> Description: measures the size of HTTP response messages (compressed).
     -> Unit: By
     -> DataType: Empty

This is a Python (FastAPI) application. Something must be wrong with instrumentation or a library.

It looks like this is ultimately https://github.com/open-telemetry/opentelemetry-python/issues/3277