In the instance I am using, and I think others I have seen in the past, the default text color for Confluence is not black, but some dark blue/grey color.
It can be frustrating when creating content. We need to change the color to black manually - and unfortunately, for whatever reason, highlighting the text and selecting black doesn't always work, so I need to change everything first to red and then to black.
When pasting in content from other areas, the default text color is used, so the color change needs to be remembered every time AND, if there are intentional color changes in the text, then bulk color changing gets trickier because that text needs to be identified for post-correction correction.