Something that’s been driving me nuts since I really started using Tab Groups is that external applications open all links in new Safari windows instead of the one I have open.
Some googling led to the conclusion that this is expected behavior - and I understand why, but it’s not what I want.
I found a work-around that someone else suggested on substack: focus modes. I don’t use focus modes for any other purpose but this appears to have worked.
Create a focus mode with a “Focus Filter,” type “Tab Group,” pick your main tab group (I have one called “Today”), and toggle “Allow opening external links in your Focus Tab Group” to on.
As long as your active safari window is in THAT tab group (“Today” for me) external links will open in a new tab rather than a new window.
Posting this in case someone else is living with this annoyance.