Developers can build a filter or sort action that works with any collection of records, from accounts and contacts to custom objects. Previously, developers couldn’t use polymorphic Apex structures in invocable actions because generic data types weren’t supported.

Create a custom action, or edit an existing one. Use the sObject or List<sObject> data type in invocable methods and attributes.

Previously, the example class would have been tied to the Account or Contact or myCustomObject__c object. But now developers create one action, and the Flow Builder admin chooses the object each time they use that action.

Source

• https://releasenotes.docs.salesforce.com/en-us/spring20/release-notes/rn_forcecom_flow_fbuilder_dynamic_types.htm?edition=&impact=