The "Yes, and launch swarm" option has been removed from the plan approval dialog. Users can still spawn teams manually using the Task tool with team_name parameter after plan approval. A hint about parallelization is now shown when appropriate: "If this plan can be broken down into multiple independent tasks, consider using a team of teammates (via the Task tool with team_name) to parallelize the work."
Evidence
Removed strings "Yes, and launch swarm", "Whether to launch a swarm to implement the plan", "Number of teammates to spawn in the swarm" and added "hasTaskTool" schema field
Strings lifted out of the shipped bundle, so the claim above can be checked against them.