Gidi Abramovich on Adding Validation to Standard Picklists using Flow and the new Record-Changed Trigger
Summer ’20 provides a new trigger: Start your Flow when a record is created or changed, just like Process Builder. Gidi’s post shows how you can use this to prevent unexpected values from being set on picklist fields.

Note that Gidi’s solution features a workaround that allows the Flow to use ‘IsChanged’ functionality:
