I have exactly the same issues as You in the new version of the Microsoft Whiteboard.
I am also not able to copy stuff between boards (the only thing being copied is text describing the thing that I'm copying like "Image" or "Handwritten text", but not the image itself), which is pretty frustrating to me, because I have to write the same things again and again, like math theorems etc.
Also, recently the board started to behave weirdly when erasing stuff, namely: when I'm erasing some handwritten text, other things get erased too in other places of the board (text that I have written before with my pan) and clicking and the undo button either doesn't work or it creates recovers the handwritten text not exactly where it was (there's like a 5 cm shift).
It didn't happen, till I received the updated version of the board, where the ruler icon was updated (the ruler still doesn't work on my side, like there is an icon, but when you click it, it only says that the ruler will be working soooon ;) And it says that already like for 2 months, so I don't have any hopes in it ever working.
Fortunately, I don't have any input lag.
Don't get me wrong. I'm a big fan of the idea of creating one cross-platform version of the Whiteboard, which looks the same and has the same features across all platforms (Windows, Mac, Linux).
I love how Edge handles PWA in general, because it creates a really nice environment for web apps.
Microsoft is constantly adding new features to the Edge browser regarding the PWAs, expanding its possibilities, but weirdly their own apps don't make use of these features. (like custom title bar, offline mode for PWA, etc.)
As far as I know, the current version of the Chromium engine allows webpages to ask for a permission to access the clipboard. And the Whiteboard should do exactly that and allow users to copy stuff between board.
Moreover, the caching system should be improved, because it takes a lot of time to create a new board (like there's a significant delay just to create an empty board).
Also, moving the tools box should be an option (where you select the pens etc.)
The idea behind the change was great, but the final product is pretty disappointing and in my opinion there should be a longer beta period, meanwhile still allowing users to be able to use the good old legacy apps, until the problems with the web based version aren't resolved.
Regards,
Adam