In this screenshot you can see that I have vampiric burst active, but I don't even get the baseline 125% (with healing booster) because of how the diminishing scaling is working.
in this screenshot I only have these two items and I get the 125%
came here to report this as well. The lifesteal diminishing return changes mean Vampiric Burst + Healing Booster loses a modest amount of Bullet Lifesteal if you buy an item which gives Bullet Lifesteal in addition to Vampiric Burst.
