I double-checked, and the favicon didn't make it into the design preview, or I would (hopefully) have commented on this earlier. But the bookmark is about the only thing really visible on most backgrounds in notifications, site switcher, and so forth: the gray circle just blends in, making it look remarkably small compared to almost all other favicons. For example:
I can see two ways to address this. One is to drop the circle and just make it a bookmark that fills most of the available space. That would be fairly straightforward. The other would be to use the entire E/bookmark logo; I assume this was rejected for whatever reason, although I'd thought it would be reasonable enough. If possible, I'd prefer this choice, I think. An extremely crude rendition, just for general idea:
I think that has a better heft to it (although the line weight got reduced too much by my crude hackery).
Anyway, thanks for a design I generally like!