Studies have shown that the excessive contrast of black text on white overstimulates the eyes, creating more eyestrain than dark grey (#444).
Here's a study showing how the overstimulation from black text on white background can cause myopia through choroidal thickening (and the reverse, with white text on black background causing choroidal thinning.) https://www.nature.com/articles/s41598-018-28904-x
If the shade is really that different, then the problem is a poorly calibrated screen, and black text on white is also going to look "totally different".