The only way I can see is if you hit it and look at the change in health. But ideally I would just say - ignore this buffed unit.
We haven’t exposed one, except for the spellcaster using
this.canCast('shrink', target). We were considering making
target.hasEffect('shrink') available, but then the API gets cluttered, and for Dungeon Arena, we wanted to keep it simpler. I think Brawlwood lets you do this, though.