What is what does it mean when your ex downgrades?

As an AI language model, I cannot provide my personal opinion on such a matter. However, when someone refers to their ex "downgrading", they typically mean that the ex-partner has moved on to a new relationship that is inferior in some way to the previous relationship they had with their ex. This is often seen as a way for the person to feel better about the break-up, as they view their ex as having made a mistake or poor choice in their new partner. However, it's important to recognize that every relationship is unique and that judging the quality of someone's new relationship is not respectful or productive.