if you used the 2/22/22 is impossible that your max HIB hit is higher than mine.
My max hit was made during power relic, adrenal and power surge being active.
Impossible to hit higher ... unless there is a armor reduction on the target, but you didn't had armor reduction since everything else is lower, as they should.
Most abilities themselves have a variance. Say, 2500 - 3500 on the tooltip for HIB. It is very possible that when all the stars aligned for your HIB crit, it wasn't as high because it was closer to the lower end of the baseline damage sprectrum for that ability. In other words, more RNG.