Understanding the intricate feedback mechanisms between phytoplankton and nutrients is fundamental to predicting aquatic ecosystem responses to global change. While unidirectional nutrient-phytoplankton interactions are well-studied, the reciprocal causality and symmetry of these feedbacks remain poorly explored. Using a global dataset of 134 lakes spanning four continents, we applied convergent cross mapping (CCM) to 593 monthly time series to identify pairwise feedbacks (PairFB) between chlorophyll a (chl a) and macronutrients (ammonium, nitrate/nitrite, phosphate, and silicate). We found that PairFB was highly prevalent (54-75%) and fundamentally symmetrical across global lakes. However, this symmetry is highly sensitive to environmental context. Accelerated warming rates systematically break symmetrical feedbacks, typically driving them toward phytoplankton-dominated control or nutrient-dominant feedback, whereas increasing latitude often promoted the formation of symmetrical feedback. Furthermore, localized factors such as lake water depth, trophic status, and nutrient co-limitation critically mediate the pathways of feedback formation and disruption. Our findings demonstrate that the structure and symmetry of essential phytoplankton-nutrient feedbacks are dynamic, environmentally contingent, and critical for understanding how lakes will respond to escalating anthropogenic pressures, providing a novel framework for diagnosing ecosystem resilience.