The bug
Other items which contain items, such as shulker boxes or crossbows, describe the content in the item lore.
However, for bee nests / hives this is not the case, making it impossible to tell if (without advanced tooltips) or how many bees are inside a nest / hive.
How to reproduce
Make bees enter a nest / hive
Break the block and collect the item
Hover over the item in your inventory
❌ There is not information about the contained bees shown
Can confirm in 21w03a.