Drawn Line Changes Brightness When Moved

Try this:

GPU settings in Photoshop are causing conflicts with certain features

Select Edit > Preferences > Performance (Windows) or Photoshop > Settings > Performance (macOS).

Make sure Use Graphics Processor is checked.

Select Advanced Settings.

Uncheck Use OpenCL and GPU Compositing, and select OK.

Select OK and restart Photoshop.

from here:

https://helpx.adobe.com/photoshop/desktop/troubleshoot/performance-stability-issues/resolve-graphics-processor-gpu-and-graphics-driver-issues.html

Try resetting the tools and/or preferences.

To restore preferences quickly using a keyboard shortcut:

Press and hold Alt+Control+Shift (Windows) or Option+Command+Shift (Mac OS) as you start Photoshop. You are prompted to delete the current settings. The new preferences files are created the next time you start Photoshop.

Note: Using the keyboard shortcut, preference files for custom shortcuts, workspaces, and color settings will also be reset to default.