My layout seems to have changed

I clicked when watching a Broadcast & everything changed view-wise

Everything is larger but less detailed

Browser zoom? Can try to reset to default with Ctrl 0. Otherwise, a link to a screenshot might help.

why are profile pages changed in such a bad way, why is message/follow/report etc now in a hamburger menu

why did you get so bored to change what was in perfectly good state

blocking someone or whatever is now unnecessarily tedious

Not sure what this has to do with OP's problem. Anyways, I presume there are a few reasons, like icons alone are not descriptive enough and since the website has to work on mobile devices as well, this clearly reduces the amount of needed horisontal space.

Then why is this not in effect only for mobile devices? And the fewer horizontal space has now changed to unnecessary vertical space

Maybe it's getting used to, but I'm not particularly enthusiastic about the hamburger menu either. Changes made for mobile should not negatively affect the desktop experience, which in my view is infinitely more important. And it seems this one does.

Maybe OP accidentally held control and rotated the mouse wheel, while accessing the Broadcast? This changes the zoom level in some browsers