When red marine macroalgae are turning more bright red it is often a sign of too much light, whilst a more white or orange colouration often is a sign that those parts die off.

More faster growing macroalgae species like Red Grape will develop more pale grapes for example when it gets too much light.

We recommend to vary the location of the macroalgae in your tank and let it adjust for a couple of days to see if the lighting conditions are better for the macroalgae.