I had the idea of having the vines attached to the logs of some of the Ultra Jungle trees be a different kind of vine than the Ultra Jungle Vines on the leaves. "Ultra Jungle Pepper Vines" would have red peppers on them, and touching them would set you on fire, apply the burn status to your whole party, and give you an achievement called "Ultra Spicy Hot". Like other vines, they are climbable (might want Fire Resistance), they spread to adjacent blocks, and they break when unsupported. When broken, these vines have a 25% chance of dropping either Spelon Berries or a new food item like Ultra Space Peppers, Ultra Jungle Peppers, or Ultra Jungle Fruit.
If you pick the Ultra Jungle Peppers drop instead of Spelon Berries, then here are some proposed uses for it, as I doubt you want to introduce a useless item. You can eat them of course, and Ultra Jungle Peppers restore 2 hunger points (1 hunger bar), have a saturation ratio of 0.6, and apply an Avoidance effect for 20 seconds. Furthermore, they can be crafted into red dye. They can also be used to craft a Weak Ultra Beast Lure or Strong Ultra Beast Lure, which increase the spawn rate of Ultra Beasts by 2.5x and 5x respectively.