The focus border keeps showing by default even when not using keyboard navigation. Especialy evadent when using mobile. There have been several people posting this same issue on the FB Group. It can be solved by setting focus outline to none but then we have to compromise the accessabilty of the site.
Thanks so much for your report!
Your suggestion is an improvement and not a bug, so I will move the thread. If I understand correctly, you are suggesting to use :focus-visible instead of :focus, right?
The browser support for :focus-visible has reached a point where we can think about it. I will address the issue within the team.