The Warlock Eldritch Blast ability has the bizarre and very unwelcome interaction of causing knockdown'd mobs to immediately recover and beeline straight for said Warlock. If timed correctly you can even witness it cancel the knockdown effect within the same combat flurry as it takes effect, which visually presents as the target enemy dipping backwards and then immediately ignoring gravity to right themselves, followed by them chasing after the Warlock responsible.
At a guess, this is some bizarre interaction of the aggro system and however Eldritch Blast calculates said AI attention. Based on several dungeon runs with people consistently using knockdown and my Warlock consistently sniping said target with Eldritch Blast, roughly 50-75% of the time this occurs, which is exceedingly bad given that it cancels the knockdown status effect outright as well as rips aggro onto the Warlock.