Steps to reproduce:
Have multiple tabs open. On a left tab open a link (eg specifically cmd click a link in news.ycombinator.com): the new tab opens to the right of the parent.
However, if you now close that tab, focus goes to the tab on the right.
Closing a tab should return focus to the "parent" on the left, not whatever is on the right.
Orion and macOS:
MacOS 11.6.2, Orion Version 0.99.108.1.2-beta (WebKit 613.1.12)