We have noticed our boots breaking at an accelerated rate, both on our realms and our vanilla servers. This is even though boots have a higher durability than the helmet. I am not sure how to go about reporting this except by sending a few screenshots of damage over 2 minutes of fighting mobs on enchanted gear with level 7 unbreaking generated from command blocks.

NOTE: we understand unbreaking only has a chance to reduce damage, but given the durability of the boots is higher than a helm we image the helm would actually break first.

The screenshots below show damage over approx 1 minute of fighting approx 12 mobs.
It compares the damage done to the helmet versus the boots.

As you can see the boots always take more damage and faster than the rest of the gear. In all test cases even with out encants boots always broke first or took more damage faster.