Reading directly from the TWAB released on April 21st it states:
Added a small delay before detonation on Champions, minibosses, and bosses - this allows the impact to stun an Unstoppable Champion and the detonation to deal bonus damage against the stunned Champion.
Damage changed to be more of an even split between impact and detonation, and increased damage across the board by ~50%.
Comparing the damage numbers from before and after the update on high health targets you can see it only received a 13% to 17% damage increase over all, (unless I'm misunderstanding the patch notes) this is shown in detail in the video linked above.
Hopefully someone sees this so they can confirm whether it's bugged or not.
Thanks for reading :)
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That Taniks clip was awful.