Hey, thanks for the report. This isn’t a bug, it’s the current behavior and it depends on your plan type.
On request-based or legacy pricing and on Free, the built-in subagents Explore, Bash, Browser always use Composer, and you can’t change the model. The only option is to enable Max Mode, then subagents inherit the parent agent’s model, but it costs more.
On token-based paid pricing, for custom subagents you can set the model directly in the .md file via the model field in the frontmatter, for example model: claude-4.5-sonnet or model: inherit to inherit from the parent. More details: Subagents | Cursor Docs