To prevent the subject from becoming black and white after removing the background in Photoshop, you can use the History brush tool to paint the original part back in. Simply select the History brush tool from the toolbar, choose the appropriate brush size and hardness, and then paint over the area that you want to restore. This will bring back the original colors and details of the subject.
Another way to prevent the subject from becoming black and white is to use the Select Subject or Remove Background commands in Photoshop. Both of these commands can quickly select your subject and remove the background from your photo. However, the difference between them is that Select Subject requires you to manually remove the background after it draws the selection, whereas Remove Background automatically removes the background for you. To use Remove Background, simply select the layer with the image you want to edit, go to the Layer menu, and choose Remove Background. This will create a new layer with the subject isolated from the background, which you can then refine further using layer masks and adjustment layers.