In widows firefox69.0.3, pub 4 forward streams, and call updatestream to join the mix, keep it for a while, find video mosaic

[cisco66666]

1,Environment and platform： 43mcu，ubuntu，software，windows：firefox69.0.3 2,Reproduce step 1，pub 720p forward stream with vp8 ，vp9,h264,vp8 2, pub 4 forward streams, and call updatestream to join the mix, and sub mix stream 3, keep it for a while, Found mosaic in mix， Like the first stream of the first graph, the fourth stream of the second graph

expected outcome： Expected to be normal video playback, no mosaic