Safari tab groups still a disaster for me... fix?

I decided to try using Safari tab groups, and am seeing bugs in the current v. 15.3 (Monterey 12.2.1 M1 MacBook Air) that were being discussed last fall. (Mac Safari 15 Bugs)

When I select File>New tab group with xx tabs:

  • The existing tabs disappear, and “reopen last closed tab” won’t restore them. The memory of them is lost.
  • The new tab group appears with tabs of start pages or empty pages, depending on how the “new tabs open with” preference is set.

Tab groups look like they’d be quite useful, and it looks like they work fine for most people. But, alas, not for me.

I could start by deleting the preference file… Is there an easier fix?