My 2c: if we were evolved to be carnivores, we'd have carnivore dentition. Our teeth classify us as omnivores and our bodies need plant nutrition. I consider any extreme, whether veganism or carnivorism to be bad.
It's also known that diets that are too high in protein cause excessive calcium secretion into the urine and can cause kidney stones too.
There was a case many years ago of two young German men who went to live in the Namib desert to avoid internment during the second world war and they managed well and because it was a desert, their diet was largely carnivorous but after about 3 years, they had to leave because one of them developed a vitamin B deficiency. The story is told in The Sheltering Desert by Henno Martin