Samsung recently launched a security update in April for the Samsung Galaxy S20 Ultra which has introduced a distinctive visual bug for the Android flagship. Many users have reported that the display has a green overlay after the latest update.
The issue only happens at a refresh rate higher than 60Hz or when the temperature goes above 40C and the device is at 5% battery
The models that seem to be affected by this problem is the Exynos 990 variant of the Samsung Galaxy S20 Ultra
Samsung has acknowledged the bug and is working on it. The solution they have come up for now is to factory reset the phone.