otel client ( dotnet client as well ) doesn’t use exponential histograms so first of all drop native histogram feature flag from prometheus configuration. https://github.com/open-telemetry/opentelemetry-dotnet/blob/main/docs/metrics/customizing-the-sdk/README.md#configuring-the-aggregation-of-a-histogram

otel client sends explicit bucket histogram which can only be converted to classical prometheus histograms https://www.prometheus.io/docs/specs/native_histograms/#otlp

OTEL_METRIC_EXPORT_INTERVAL in otel client sdk is 60 sec by default while as garafna expects it to be 15 sec. We have two choices either set it to 15 sec in otel client as mentioned here https://prometheus.io/docs/guides/opentelemetry/ or change scrape interval to 60 sec in grafana as mentioned here https://grafana.com/blog/2020/09/28/new-in-grafana-7.2-__rate_interval-for-prometheus-rate-queries-that-just-work/