The phrase "problematic nature" means that something has aspects or qualities that create difficulties or challenges. It refers to a problematic or troubling character or behavior of something. Full definition
Recent events, including when a pig died after being fed alcohol, have revealed the potentially problematic nature of this activity. (travelandleisure.com)
Artist Josiah McElheny discusses the intentionally problematic nature of beauty and seduction in his Total Reflective Abstraction (2004) installation, on view at Donald Young Gallery in Chicago, as well as works by fellow artists and architectural masterpieces such as Renaissance palaces. (art21.org)
Putra's work has a similar problematic nature to it; a female figure whose mouth has been slit apart and stuffed with corals, or a woman dressed in a trench coat with plants growing from her head — there is a sense of darkness to his works. (theartling.com)