What happened to the prophets of Baal after the contest?

Answer: They were killed

Elijah had the prophets of Baal seized, brought down to the Kishon Valley and slaughtered there.

“Then Elijah ordered them, “Seize the prophets of Baal! Do not let a single one escape.” So they seized them, and Elijah brought them down to the Kishon Valley and slaughtered them there.”— 1 Kings 18:40 (BSB)