The short answer
No. You can join an existing Professional or Enterprise team and open its team overview with a personal Free plan. Your personal plan stays in place. Other plan-dependent features and permission to create a team are checked separately. Joining does not automatically unlock every feature of the team's plan. An existing paid subscription continues until you change or cancel it separately. Your personal credits are also kept. While the team pool is active, the sidebar shows the team pool instead of your personal balance. You still find your personal balance under Billing, and the sidebar shows it again once you leave the team.