The qualityLimitationReason property of the RTCOutboundRtpStreamStats dictionary is a string indicating the reason why the media quality in the stream is currently being reduced by the codec during encoding, or none if no quality reduction is being performed.

This quality reduction may include changes such as reduced frame rate or resolution, or an increase in compression factor.

The amount of time the encoded media has had its quality reduced in each of the potential ways that can be done can be found in qualityLimitationDurations.

A Map whose keys are strings whose values are none, cpu, bandwidth, or other, and whose values are the duration of the media, in seconds, whose quality was reduced for that reason.