Activity indicator for pinned tabs may be triggered by opening browser
I've been noticing the activity indicator under my YouTube tab even when I haven't visited the tab at all since opening the browser: the tab is still the placeholder white page that EphyEmbed shows before loading the real page. It seems the activity indicator for pinned tabs may be triggered by opening browser. This doesn't always happen, though. (Maybe it's timing-dependent?)
See screenshot:
What happened here was that, after launching Epiphany, in a fraction of a second the active web view seemed to move from left to right as tabs are launched. It seemed like the activity indicator was added to the tabs when this happened.