Minecraft shader 1.15.2 does not work?

I wanted to play version 1.15.2 with shader for a long time and downloaded optifine and matching shader for the version. Has worked with every version so far. Now I have done the same thing as always and when I go to graphics settings it says "Shader…" but so gray and I can't press this "folder" to select a shader.

Why is it no longer possible? Is that because this is still the preview version?

Could you have activated "Fast Render"?

Otherwise it could be that your current version simply does not support shaders

This is because Optifine for 1.15 is not yet working properly. So yes, that's because of the preversion.

Thank you