In addition to the brand new affixes in Dragonflight Season 2, the Explosive affix is getting some changes in Dragonflight Season 2 Mythic+.
Blue Post
In the original Blue Post, Blizzard announced the following:
Updated Affix: Explosive – Fewer Explosive Orbs spawn, but they now have substantially higher health.
Datamining
From datamining, this isn’t the only change that was made to Explosive:
Deals Fire damage equal to 40% targets’ health to enemies within a 60 yard radius.