Custom fields that are already created will now be visible while adding a deal card, setting new automation, or while editing the existing one and in the contact 360 section.
Custom fields can be added while creating a new pipeline or you can edit and add in the existing ones. While adding a deal card, if you click on More Options you will get the custom fields visible.
If you create automation for the pipeline where you have already added custom fields, you will be able to see the custom field in the Tags section too.