[SDPhantom]

I'm guessing this is for retail as the function replaced doesn't exist in classic. That being said, this is the original function. It appears to have been changed for Dragon Flight.

function NameplateBuffContainerMixin:ShouldShowBuff(aura, forceAll)
    if (not aura or not aura.name) then
        return false;
    end
    return aura.nameplateShowAll or forceAll or
           (aura.nameplateShowPersonal and (aura.sourceUnit == "player" or aura.sourceUnit == "pet" or aura.sourceUnit == "vehicle"));
end

AddOns\Blizzard_NamePlates\Blizzard_NamePlates.lua:662

aura seems to be a table returned by C_UnitAuras.GetAuraDataByAuraInstanceID() / C_UnitAuras.GetAuraDataBySlot().