So I've noticed this ever since I made my first Enchantment Table on the Bedrock Edition but haven't thought of reporting it till now.

Basically enchantments seem to be linked together with other similar items. Pickaxes seem to share the same enchantment options as Shovels. Swords seem to share the same enchantment options as Axes. And Chest-plates seem to share the same enchantment options as Leggings.

I'm not sure if this is an intended thing or not but I don't remember this being a thing in any other version. So I apologize if this is something that was supposed to be a feature and not a bug.