Sometime in my lifetime, we almost completely stopped using the word “supper.”
This is a tragic loss, if for no other reason than it has led to confusion.
Besides “brunch” and “lunch,” the only other post-breakfast word we have is “dinner,” and dinner can alternatively mean a noon meal or an evening meal. Importantly, dinner has a generic root that is still extant: to “dine.”
So while we can “sup,” that would be archaic, and it could create confusion with the common slang contraction for the phrase “what’s up?”