It will cause a color variation.

If can’t put a rug how are you supposed to walk on it in the sun? Burns feet and too hot for a dog.

Trex decking does get hot in the sun, and on a hot day, it could reach temperatures much higher than the outside temperature. Trex manufacturer keeps improving decking products by trying to make decking cool down faster.

You will have heated decking with most composites, and even PT decking, in comparison, will get hot in the sun, only a few degrees cooler than composite.

With that said, there are always ways to try to avoid the heat by using lighter color decking, and you can also provide shading using pergolas or other means of shade.

Good luck

Living in the South, we should have been asked if it was under cover. Hard to put rugs or pergolas over an elevated pool. Kind of defeats the purpose too.