>>> PS: I also have an unfinished implementation of more fancy looking
>>> tabs with rounded corners that would take more than 2 weeks to
>>> complete but this is of lesser importance and thus has lower
>>> priority.
>> That sounds very nice, and will help Emacs look more modern and user
>> friendly.  Is there any way to make an exception to include this on
>> the Emacs 27.1 branch?
>
> I've just tried the tab modes for the first time, and would describe
> the current default look as "functional", so if the proposed fancier
> look is a substantial improvement, then I'd be in favour of either
> allowing the extra time to develop them, or else allowing them to be
> merged later as bug-fixes.
>
> Perhaps it would be useful to see a screenshot showing the difference?

I'm still not sure if a fancier look is worth the trouble,
especially since in some sense it's a change for the worse:
it takes too much screen space, so less tabs can fit into the tab bar.

Please see the difference: the first image is the current tab shapes,
on the second image you can see that less tabs can be displayed
on the tab bar: