When you unlock new recipes, the information on the top right corner appears. If you immediately press "Save and Quit to Title", it will stay while the game is saving. The video below shows the issue.
Steps to Reproduce:
Grant all advancements
While the toasts are showing, save and quit
Expected: The toasts will not show during the "saving world" screen
Observed: The toasts show during saving, and go away when you are in the main menu
Yes, but this is most likely intended, as it has always been this way.