Context: the grabby hands are an extra layer to be added to images that's going around JP twitter
I think that this trend is another app filter situation where artists (and Danbooru users) would upload cropped* dupes of existing posts with something added in {arm(s) in this case}.
I'm guessing she had the sudden realization that she has indeed changed, which brought her happiness (hence her apparent tears of joy). Apparently Kafka and the Trailblazer are destined to change one another; and achieving such change is one of Kafka's main goals.
Not traced. Kafka's legs and feet are on different poses than Asta's. If anything this reminds me more of the one by hinagi #6297394 which still isn't traced.