This time no IPv6 is mentioned. You seem to have changed more things than dynamic bitrate then?
This time no dns issue seem happened, but that can be a misleading fact (luck, right timing aso.)
The bandwidth demands for streaming are quite higher than those for gaming! Gaming typically is bound to the rtt (round trip time), enforcing small data packets to be transferred in a constant and fast timely manner.
Streaming enforces steadily high bandwidth together with sturdy constant fast transportation throughout the net.
I don't know the specific settings at twitch side. Regarding your streaming. Are there settings comparable to the Youtubes latency settings (more stability due to longer delay/latency accepted)?