This issue has been going on for months now.

Certain streams have been buffering until they are 8 - 10 seconds behind.
It usually buffers 2 - 3 times, until the stream is 8 seconds behind, and then it runs with no more buffering.
At first I thought it was just random streams, but after I posted about the issue on Reddit, someone pointed out that it's only happening on stream with less than ~100 viewers. Once a stream gets over 100 - 150 viewers, there's no more buffering.
I usually watch stream with lower viewercounts, and interacting with the streamer when the stream is 10 seconds behind is very annoying.

I have submitted multiple tickets, but I only get automated responses with "clear your cache", or "we can't find any issues on our side, please contact your ISP".

It's pretty obvious that Twitch is limiting bandwidth to streamers with lower viewercounts, and it's getting really frustrating using Twitch like this.

Hope this will get fixed soon.