Zombies generally fear light; that's common knowledge.
So when Liu Liang saw the light, he inexplicably felt a sense of relief wash over him.
As he turned his head in panic to look at the zombie, he noticed that it indeed seemed to be moving more sluggishly.
Strictly speaking, it appeared to be very fast only at the moment it pounced initially, but then, just like deflating, its speed quickly diminished.
Otherwise, with Liu Liang's tumbling and scrambling escape, he would have been caught long ago.
Watching the zombie stagger toward him step by step, its gait growing slower and slower, Liu Liang was no longer as tense; he took several deep breaths and felt his racing heartbeat gradually returning to normal.
"Ha, not so tough now, are you?"
Backed by the light, Liu Liang felt his confidence growing and even remembered his role as a streamer, intending to spice up the show a bit.