I could've sworn firefox had an "all tabs" preview button that looked like 4 blocks in a grid, before the Australis era. Can't find any pictures/video footage of it in action however.

Best I could find is: https://www.askvg.com/how-to-enable-ie-like-quick-tabs-featu... But I'm not sure if this landed, or if it ended up functioning differently.

i could have sworn the same, at least as an extension.

i just found this extension, but that's brand new: https://addons.mozilla.org/en-US/firefox/addon/ff-tab-expos%...

Tab groups used to do that