When writing histogram metrics, and there is an exemplar for the +Inf bucket, then the +Inf bucket is added with the value of the previous bucket:
https://github.com/prometheus/client_golang/blob/main/prometheus/metric.go#L188

This is incorrect, as the cumulative count of the +Inf bucket should instead be added with the total count of the histogram datapoint.

The above behaviour results in invalid values being reported for the +Inf bucket.