Setting Access Permissions: In the Power Platform admin center, you can set permissions for Copilot Studio authors. By default, all users in your Microsoft Entra tenant will have Copilot Studio authoring access. If you need to restrict authoring access, you can change the default permissions and choose a different Security Group
Go to copilot studio->power platform admin center and try changing the permissions there.
Also try referring to below doc if that doesn't help
https://learn.microsoft.com/en-us/microsoft-copilot-studio/admin-share-bots?tabs=web

Hope this helps!