Xiaoming was kept in the dark by his parents and finally suffocated? What does that mean?

This is a cold joke. The original meaning of "being kept in the dark" means that people are confused and stupid, ignorant of the truth and have no concept of related things. Metaphor is not knowing the truth and being cheated.

But in this sentence, "in the dark" means "hiding in the dark" and "stuffy in the dark". Finally, Xiao Ming suffocated and died.