Unleash 4.21: Environment-dependent variants, visible API traffic, and service accounts

Unleash 4.21 introduces several enhancements centered on fine-grained control, particularly through environment-dependent variants, which allow modifications specific to certain environments without affecting others, thereby facilitating more precise access control and integration of change requests. The update also includes UI improvements, such as the ability to check active variants by hovering, and features like pushing and copying variants between environments, eliminating migration concerns for existing projects. Additionally, users can now monitor Unleash API traffic directly via an overview tab, and enterprise users benefit from the introduction of service accounts, which provide more detailed permissions for integrations than traditional admin tokens. Unleash 4.20's feature to pin favorite feature flags for easier sorting is also highlighted, with all new features detailed in the release notes.