On Java, you can apply Unbreaking, Mending, and Curse of Vanishing on a brush. However, you cannot apply those enchantments on a brush in Bedrock Edition.
Step to Reproduce
1. Get a brush.
2. Try to apply it using /enchant commands.
3. Also try to apply the enchantment with an anvil.
Observed Result
The game refuses or unable to apply the enchantments on a brush.
Expected Result
You should be able to apply Unbreaking, Mending, and Curse of Vanishing enchantment on a brush.
Confirmed