It’s the first moment where Amity looks genuinely happy to be around Luz, as you can see her facial expressions change from scared of this monster, pauses, looks at Luz, and actually feels happy during this terrifying moment. Every moment afterwards, she don’t act snotty but
rather happy and somewhat protective of Luz. She may not speak much in the end of the ep but you can tell that in every episode afterwards, something changed in Amity during that night. And she seems to start liking Luz more and more with every ep, which eventually leads to her