Current Bloodthirster is worthless
Bloodthirster has been an item of note in past updates; with the old stacking gone for a while now and the update to the now-unique lifesteal. However, the current variation of the shielding passive is, in all honesty, equivalent to having more max HP in combat and nothing else.
There is absolutely NO advantage that this shield has over HP: It doesn't scale independently from lifesteal with reduced absorption, it cannot deal bonus damage based on the status of the shield, and it has no ability to trigger upon being attacked, similar to Yasuo's passive
Those are just my suggestions, but for the love of my ADC's, this current one cannot stay