Looks like Google Photos is trying to make it easier for you to share your photos with your family and friends. Android Police shares some screencaps featuring the new design. If you try to share photos, there’s a new screen with a carousel-like photo picker to make it easy to look for photos you took around the same time as the one you shared. You just need to tap them to add to the list of photos to send.
And with Google introducing Family groups, Photos is integrating a new Family group sharing target in the list. This’ll make it easier to share photos in one fell swoop. You can still of course deselect people and add ones you’d like to share these shots with.