how to put a ribbon on a featured image

Hi there,

Are those categories?

If so since you are already using a content template to display the post, you can add a button block with dynamic property to display the property:
https://docs.generateblocks.com/article/buttons-overview/
https://docs.generatepress.com/article/dynamic-data/

An example like this should help:
https://youtu.be/-ZTQP_KA2xE

Thanks!

No problem :)