Books having unrelated enchantments.

When I play Minecraft, fishing or checking chests from structures, I find enchanted books with enchantments that aren’t physically possible to combine. Now, in both of the pictures, you see that (In picture A.) Feather falling and efficiency don’t match. Feather falling goes onto armor, while efficiency goes onto tools. And in the other picture, picture B. You can find that power, doesn’t go with density. Nor does sweeping edge go with the other two too. And P.S. the second picture was taken in Java edition, so both of the versions have this problem. I can choose what enchantment I want as long as I choose the correct weapon to put it on, but i don’t think enchanted books should have multiple enchantments on them. If this is something I didn’t know about, sorry for wasting your time. But otherwise, this seems like a bug.