In Safari 15 for macOS that was released a while back (and the beta I believe) you had two options for the tabs. Both of them had them look more like regular buttons than a tab from a tab index, something that has been highly debated since it was first announced:
But with the release of Monterey, Apple had reverted back to the old look (there is still an option called compact that puts them on the same row as the address bar):
