TYPO3 Core

Patch set 2 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/81493

Patch set 3 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/81493

Patch set 4 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/81493

Patch set 5 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/81493

Patch set 6 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/81493

testing has revealed that this is inconsistent.

In TYPO3 12 is works with on Ubuntu

I can throw in MacOS:

Safari: Does NOT work
Chromium (Brave): works
Firefox: works
MS Edge: works

BTW: In Safari the issue not only affects the bootstrap tab order, but also the top action row ("Close / Save / View / Create / Delete") is not accessible. Tabbing only goes to the single "button" in that row, and skips all other "links".

Tested in v12 and main.

I'd say so too. I would declare Safari to not follow proper HIG standards here and it'll hopefully get addressed as a brower "bug".