Daun ubi tumbuk is basically pounded cassava leaves cooked down in coconut milk with aromatics and usually ikan bilis or anchovies. If you have never had it, think of it as Sarawak and Sabah's answer to a braised greens side dish, except the gravy is rich, slightly fatty, and really good with rice. At 270 calories for a side dish, it is not exactly a free food, but it is not crazy either. The cassava leaves themselves only contribute about 30 calories. The santan is doing 135 calories of work all by itself. Be honest with yourself about how much gravy you are ladling over your rice. Fair warning on the numbers: this is a genuine ballpark estimate because there is basically no hard nutritional data published for this specific dish, and every warung makes it differently.
What actually moves the maths is simple: how much santan and how much oil. The tanpa santan version (just oil, garlic, anchovies) drops to around 120 calories for the same-sized serving, saving you 150 calories. The light coconut milk version sits at 180 calories. Go full masak santan pekat with generous coconut milk and maybe some udang or offal thrown in and you are looking at 400 calories from a side dish alone. The ikan bilis adds about 45 calories but also gives you a protein hit for the size. If you are eating this at a nasi campur counter, watch the portion size because the serving spoon will give you whatever it gives you, and the gravy tends to be generous.