Why are my streams jerking?

For 2-3 days I have had problems watching live streams. As soon as I switch to HD, they start to jerk every few seconds, sometimes it reloads briefly. If I watch Netflix or Amazon Prime, I don't have these stutters and that's HD too. I've already done various speed tests, so it's definitely not the internet. ONLY for LIVE streams on Twitch and Youtube. If I watch videos there, everything goes great. I switch e.g. With Twitch on 480p it also runs without jerking, it only jerks from 720P. And as I said, it's only been like this for a few days, before everything was normal. I also renewed the graphics card driver and changed the browser, but unfortunately it made no difference. Does anyone know? =

This is due to Twitch itself. You mean, you have to show the low in the stream.

Nah on YOutube I have the same problem and that was never the case before. I could always watch 1080p myself without any problems, no matter which stream or platform.

It may be the device, or your Internet provider is currently faxing