I am not sure if this is a bug in the obsidian block itself, or in the power of diamond pickaxes, or in block breaking in general.

Steps to reproduce

1. Place a block of obsidian.
2. Mine the obsidian with a diamond pickaxe while using a stopwatch to track the amount of time it takes.

Expected result

It takes almost 10 seconds to mine a block of obsidian, like in Java Edition.

Observed result

It takes about 7 seconds to mine a block of obsidian.