Here is a step-by-step guide for you to follow and fix the flickering screen issue on your macOS 10.15.
Step 1: First, restart your Mac by going to the "Apple" menu and click on "Restart."
Step 2: Next, update the operating system on your Mac.
Step 3: From there you need to reset SMC (System Management Controller). The steps involved vary according to the type of Mac you are using. If you are using one with a removable battery, you need to shut down the computer and disconnect the Magsafe power adapter. After that, remove the battery, press and hold the power button for 5 seconds and release it. From there, you can connect Magsafe power adapter, the battery and power on your computer.
macos 10.15 screen flicker solution
Step 4. You also need to reset NVRAM (or PRAM). To do so, by first shutting down your computer. When restarting it press and hold Option+ Command+ O+ R simultaneously for a few seconds and the device will restart.
Step 5. If you are using MacBook Pro, go to "System Preferences" and head to "Energy Saver." Now, search for "Automatic Graphics Switching" option and untick it. Remember this option is not available on Mac Airs.
fix a flickering screen issue
Step 6. You can diagnose the flickering screen while in safe mode. To enter safe mode, first close all the running apps on your computer and shut down your Mac normally. From there, you need to restart your Mac by pressing and holding the power button and shift the key until the Apple logo appears. Release the power button and keep pressing the shift key until the login window appears. From there, you can release the shift key since you are now in safe mode.
At this point, the flickering screen should have now disappeared. From there, you can restart your computer normally and you will have a fixed flickering screen with macOS 10.15.
Step 7. If the above steps have not stopped the Mac screen from flickering, you can try and uninstall the Firefox application. According to some users, they have reported that uninstalling and reinstalling Firefox browser is macOS 10.15 screen flicker solution.
Step 8. Assuming you have tried all the above macOS 10.15 screen flicker solutions and you Mac screen still flickers then you can try this last option. Try and create a new user account. You can do this by going to "System Preferences," select "Users and Groups" and then click on New user account and create the account. This should stop the screen from flickering, but if you see the error still persists then delete the newly created user account.
Regards,
Rachel Gomez