Why is twitch lying like this?

Every other site (Netflix, Youtube [also live], etc runs without problems in 1080p60fps

only twitch is always at a standstill and switches the quality to 480p and has still images

We had a 16K line, now 32K and the problem is still there

Have you accidentally deleted your cookies and tried again?

Or maybe use a different browser, for example I had problems with Opera, YouTube always loaded forever and now I use Chrome and everything works fine