The right-hand "timeline" thing is broken
5 days later
Thank you for posting this here, I'll look into this when I can
Is anyone else affected by this?
7 days later
I wasn't able to replicate this with scaling 159%, in Windows 10 with display resolution 1152x864 in a VM
It's possible with the enlarged text size and screen resolution it's confusing the browser into desktop / tablet mode.
There are reducing motion settings where it will alter behavior of the slider. This is normally explicitly set.