problem with lightroom, urgent, help me please

Hello. Please I need urgent help. For days I've been calling adobe but nobody solves my problem. I have a problem with lightroom that makes it impossible to work with the photos. When I move the mouse and the arrow moves, the photo becomes lighter or darker depending on where the arrow is. This makes it impossible to know how much light and exposure is needed for this photo. Specifically, when I move the arrow into the gray window of the lightroom screen the photo gets darker. When I move the arrow to the photo it gets lighter. It is not possible to know the true light of the photo in this way. The same thing happens when I increase the size of the ligtroom screen. As soon as I pull the general lightroom screen sideways or upwards to see the photo in a larger size, the photo gets more light. I tried to talk to several adobe technicians in the chat and none solved anything. They made me change my Mac's system from mojave to catalina, made me downgrade from version 9.2.1 to 8.2.1, another one tried uselessly to calibrate the colors of my monitor, etc. Has anyone there ever had the same problem I'm having or can you help me?
thank you