When there are multiple Start Page tabs open, navigating in and out of bookmark folders appears to be linked between them. This can be seen with the following steps:
1) Open two tabs, both Start Pages
2) On one of these, navigate into any Bookmark Folder
3) Switch to the other one
4) That same folder will be open on both pages
This isn't a problem in itself but it causes several strange and broken behaviours. One example:
1) Open two tabs, both Start Pages
2) On the first tab, navigate into any Bookmark Folder
3) Switch to the 2nd tab (or open a new start page)
4) Press the button to navigate back out of that Bookmark Folder
5) It will navigate back TWO levels instead of one (to Favourites/Bookmarks Bar/Bookmarks)
This behaviour is somewhat inconsistent. Sometimes a "double back" happens like described above, other times the back/parent button doesn't work at all. Sometimes you can even get the contents of one book folder overlaying the contents of another folder or parent folder.
I've not attached a video because I don't wish to show the world my bookmarks but it's fairly easy to replicate the issue. Just open multiple start pages, navigate in and out of bookmark folders on different tabs and it won't be long before something breaks.
It seems that the Start Page shares its "navigation state" across multiple tabs and this is causing a bunch of issues.
I would expect each Start Page tab to have its own separate "navigation state". Not only would this (probably) fix the bugs I've described it would allow us to have multiple start pages with different bookmark folders open at the same time.
Version 0.99.126.1-beta (WebKit 618.1.2)
Sonoma (14)