"Uneven tone" refers to a way of speaking or writing that lacks consistency or balance. It means that the message or expression is inconsistent in style or mood, making it seem irregular or abrupt. Full definition
This causes uneven tones, dry texture, and more breakouts than usual. (mindbodygreen.com)
Direct and prolonged contact with UV rays can bring back or worsen your skin concerns like uneven tone, pigmentation, oily skin, spots, etc.. (makeoverly.com)
Stone's misguided efforts to turn Alexander into a drama of Shakespearean proportions undoubtedly plays a big role in the film's wildly uneven tone, which flits wildly between talky period piece and flamboyant melodrama (often within the space of a few scenes). (reelfilm.com)