How were early, subtle variations in Mars' brightness and color interpreted by observers with less powerful telescopes?

As evidence of seasonal changes like thawing polar ice caps or shifting water bodies

During the era utilizing early, less powerful telescopes, observers noted that the surface of Mars appeared to fluctuate in both brightness and color. These subtle changes were not immediately attributed to intelligent construction but were interpreted by many astronomers as indicators of seasonal terrestrial processes. The prevailing hypothesis was that these variations corresponded to the thawing and freezing cycles of polar ice caps, or perhaps the seasonal expansion and contraction of large bodies of surface water, such as oceans or seas, suggesting an Earth-like environment capable of sustaining life.