Grey square appears when I click with the soft round brush selecting the mask in curves adj layer

I am facing a problem since I updated Adobe Photoshop 2024 to version 25.9.1. I extracted a subject using the ‘Select and Mask’ option, and beneath this layer, there is a background layer. I created a ‘Solid Color Adjustment Layer’ above the extracted subject, choosing medium grey as the solid color with zero saturation and set the layer properties to ‘Color’. Then, I created a ‘Curves Adjustment Layer’ beneath the ‘Solid Color Adjustment Layer’ and clipped it to the subject layer to adjust the tones only for the subject. After that, I created another ‘Curves Adjustment Layer’ above the previous one and inverted the mask, clipping it with the underlying ‘Curves Adjustment Layer’. I selected a soft round brush, selecting the mask on this layer, and set the brush color to white as the foreground color. When I click on the subject, a grey square appears on the canvas. When I brush over the entire picture, it disappears. I am attaching a video for your assistance. I am also attaching my computer configuration. I have an MSI GeForce RTX 3060 Ventus 2X installed in my system.