Currently, there's no visual distinction between unread tabs opened in the background and tabs you've already clicked on.
Firefox could have the option to show a subtle indicator on unread tabs, like the triangle displayed by Vivaldi.
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Thanks for the comment! This is definitely something we can investigate in our quality improvement efforts.
Yeah that would be very nice. It is already a thing for tabs sent from other devices, so why not make it for regular tabs as well?
1000x yes, needs to be an option. In the meantime, there is an extension (plus userStyles.css) that can help: Unread Tabs Restorer
I solved ithttps://addons.mozilla.org/ru/firefox/addon/unvisited-tabs-indicator/