There can be multiple reasons for screen flickering issue on your Mac. Some common reasons for the issue is in-display resolution, inappropriate working of Energy Saver, etc.
However, if your Macbook screen is flickering, there are few things you can try to troubleshoot the issue:
1. Check for software updates: Ensure that your Macbook's software is up-to-date. You can check for software updates by clicking on the Apple menu in the upper left corner of the screen and selecting "Software Update."
2. Restart your Macbook: Sometimes a simple restart can resolve display issues. Try restarting your Macbook to see if the flickering stops.
3. Check for loose connections: Make sure that the cables connecting your Macbook to any external displays or accessories are securely plugged in. If your Macbook is connected to an external display, try unplugging and replugging the display to see if that resolves the issue.
4. Adjust display settings: Try adjusting the display settings on your Macbook. You can do this by going to System Preferences > Displays and experimenting with different resolutions and refresh rates.
5. Reset the SMC: If the above steps do not resolve the issue, you can try resetting the System Management Controller (SMC) on your Macbook. The process for resetting the SMC varies depending on the model of your Macbook, so you should consult Apple's support website for instructions.
6. Contact Apple Service Provider: They may recommend that you bring your Macbook in for repairs or offer other solutions to resolve the issue.
Hope it helps!