Mysterious numbers displayed by tabs and bookmarks

[Odin2]

I'd like to know what these numbers represent, and how I could hide them: (1) A small white number in a red circle appears as a subscript at the bookmark for my server's Web mail (Zimbra). My ISP says it's put there by my browser. (2) Small numbers in squares appear as superscripts at some other bookmarks. I see the number 1 [black text, red background] at my bookmark for NoScript; and I see the number 2 [white text, black background] at my bookmark for ABP. Any explanation would be appreciated. I'm using v. 63, but the Zimbra subscript appeared as well when I was using Fx pre-Quantum.

[jscher2000]

Tabs show the site icon and the title of the page set in the <title> tag. Some sites add a number of new unread messages to the title when their tab is not active, as a kind of notification. Others may change their icon (I noticed recently that outlook.live.com adds a dot to its icon). Are you seeing a site icon change on the tab on the tab bar?

Bookmarks do not normally get any kind of special badge on them, and sites certainly couldn't do that on their own. However, if the site icon of the bookmark synchronizes with a changed icon on a tab, perhaps that would explain what you see there.

For NoScript and ABP, are you sure it's a bookmark and not the extension's toolbar button? Extensions have control of the appearance of their own toolbar button and may use that to convey information about such things as the number of items blocked in a page.