RTCOutboundRtpStreamStats.qualityLimitationReason - Web APIs
syntax var qualitylimitationreason = rtcoutboundrtpstreamstats.qualitylimitationreason; value a map whose keys are domstrings whose values come from the rtcqualitylimitationreason enumerated type, and whose values are the duration of the media, in seconds, whose quality was reduced for that reason.

RTCOutboundRtpStreamStats - Web APIs
qualitylimitationreason a value from the rtcqualitylimitationreason enumerated type explaining why the resolution and/or frame rate is being limited for this rtp stream.