[Tab groups] New tabs from group should always stay in that group

[Minerharry]

If a new tab is opened from a member of a tab group, currently the new tab will not be part of any group, or, worse, become part of the next group over if two tab groups are next to each other. This behavior might be affected by tab-opening settings, e.g. if new tabs are next to the source tab or at the end of the tab list. In the case of new tabs being next to the source tab, the behavior should 100% be that the tab remains in the original tab group.

[Jon]

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[jeremiabert]

I have the same issue. If two tab groups (tab group A & tab group B) are next to each other and I "Open Link in New Tab" from the last tab in tab group A, it opens up in tab group B.
Even more confusing if tab group B is collapsed.

Expected behavior would be for the new tab to open in tab group A.