Starting with 2.52.0 (shipped in 4.16) Prometheus will increment the metric "prometheus_target_scrapes_sample_duplicate_timestamp_total" when bumping into "duplicates" while scraping a target.

The alert "PrometheusDuplicateTimestamps" may start fire (just after the upgrade) if there are some targets unintentionally exposing duplicates (or relying on the old behaviour). The new warning logs could be confusing as well.

We should make sure to document this new behaviour:

• release notes?
• runbook for PrometheusDuplicateTimestamps (maybe this is sufficient)

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See: https://github.com/prometheus/prometheus/issues/14089