Salesforce introduced a new Errors and Warnings pane that lists all issues that prevent you from saving and activating a flow. The pane includes links to the flow builder canvas that help you identify the source of issues. You can show or hide the new pane with the Show Error button, which includes a notification badge that displays the total number of issues to address
How: Create/open a flow, and click the Show Error icon in the button bar to see the list of all errors or issues

