Permissions and the FinancialForce security model are being redesigned to provide you with a robust and focused approach to managing user security. A set of functional permissions is being delivered in Spring 2021 and will be present in your org. As this work is being delivered over multiple releases and is not complete, you must not implement the new functional permissions until the work is finished.
Salesforce introduced permission set groups in their Spring ‘20 release. Permission set groups add an additional level of control to permission sets. All the benefits of using profiles are now also available for permission sets, without the administrative overhead. For more information, see the Salesforce release notes for Spring ‘20, "Permission Set Groups: Greater Flexibility in Granting Permissions (Generally Available)".