I know that SE only supports 100% scale factor (and doesn’t support mobile browsers in full web at all) on their sites. But before today top bar worked well even after zooming on my iPad. Here is the video:
Looks like the button tap positions are wrongly shifted while page is zoomed. This is probably happened after the “help” button returning to the top bar.
Shifting the page also leads to the same behavior. E.g. empty review queue page may not fit into screen horizontally and can be shifted to the left (when top bar is sticky, like on SO) on the my device, i.e. no zoom here:
For me at least two sites are affected: SO in English and SO in Russian.
I use iPad Pro 10.5 iOS 11.2.1 Google Chrome.