Bug Report

I have been playing Volibear a few games today and I have noticed that there is an issue where I will die and check my damage report and it will say roughly 2k less damage than hp i have. For instance, I have 5.2k hp on voli and i go into a team fight (with full hp) and the damage report after i die says only 3.2k damage was dealt to me. I however am not sure if this is just an issue with the damage report or with the actual hp on the champion. I have noticed this a few times and still and very confused about it. Thank you.