https://codepen.io/jpzwarte/pen/abQJgeo

The above codepen has 4 examples of popover usage:
1. <div popover> with <button autofocus> inside it
2. <dialog popover> with <button autofocus> inside it
3. <x-popover> custom element with delegatesFocus: true and <button autofocus> in the shadow root
4. <x-popover> custom element with delegatesFocus: true and <button autofocus> slotted

1, 2 and 4 work fine in STP 173 (4 is broken in Chrome 114 and Chrome Dev 116)

3 is broken in STP 173 (works fine in Chrome).

I expect the <button> in <x-popover> to have focus when the popover is displayed. It hasn't. 
It is unclear what does have focus though. The original <button popovertarget> button is not it.