Temporary containers will do that https://addons.mozilla.org/en-US/firefox/addon/temporary-containers https://addons.mozilla.org/en-US/firefox/addon/temporary-c

Temporary containers will do that https://addons.mozilla.org/en-US/firefox/addon/temporary-containers https://addons.mozilla.org/en-US/firefox/addon/temporary-con... All urls that are not "pinned" to a container open in a temporary container.