Please open NVIDIA X Server Settings > X Screen 0 > Antialiasing Settings and check if you have manually enabled FXAA. It could be the cause. (bug 1717453)
Bug 1718386 Comment 10 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
Please open NVIDIA X Server Settings > X Screen 0 > Antialiasing Settings and check if you have manually enabled FXAA. It could be the cause. (bug 1714483)