Availability Group- Redo Rate displayed on AG Dashboard vs Perfmon counter

I am bit confused on checking the metrics for REDO Rate KB/Sec from Always on AG dashboard which for some scenarios matches with perfmon counter Database replica : Redone Bytes/Sec ( hopefully its correct counter for redo rate via perfmon) and sometimes not at all.

Most of the times when there is lot of activity ongoing, my belief is that AG dashboard and DMV shows REDO rate for e.g. 40 MB/Secs at given time which matches with perfmon counter.

However during less activity time or nothing much to send over to sec, REDO Rate on Dashboard and dmv seems to be showing incorrect values compared to perfmon counter.

Not able to understand which value is correct and how to analyze. Any idea why or is it bug in dashboard?