We are sorry to hear about your gaming experience with your beloved Samsung Galaxy device having issues with blue flashing line, lag, and auto-setting the volume down, and we apologize for the inconvenience it caused you.
I really understand what you are going through, uncertain of what's causes it, and if it happens to me, I will feel the same. But don't fret; we are here to guide you, and offer solutions to restore your device to optimum performance.
If the doesn't work, you may submit an error report through the Samsung Members app as follows:
Step 1. Long press Samsung Members icon on Apps screen and tap Error reports.
Step 2. Tap OK on agreement popup to send system log data.
Step 3. Select Symptom category "Application" and "Slow device".
Step 4. Describe the problem in details and SEND.
How to submit an error report on Samsung Members app? | Samsung PH
Also you can check the Game Settings and the mobile network service provider to optimize gaming performance.
For more assistance and guidance, you may contact us via our online Samsung Customer Care support channels below.
Thanks for sharing what you have experienced, noticing that it only occurs while playing games. Your beloved Samsung Galaxy devices have built-in safety features that are turned-on in order to protect them from overheating. When you use features or apps that require more power or use them for extended periods, your device may temporarily heat up due to increased battery consumption. Close any running apps and do not use the device for a while.
And to stop it from overheating, close all active and background apps and remove the phone's case to let the heat disperse.
Also, if your device has a Game Launcher, it is there to help you organize all your games and manage your in-game preferences, such as sound settings, game plugins, shortcuts, and screen refresh rate. You can also use Game Booster tools to block app alerts and notifications while you’re in the middle of gaming.
I was confused at first but one time I cleared all notification and open a game then noticed the blue line pulse thing on the corner when I pulled down the notification bar it was from FB Messenger, tried it with other apps and the blue light pulse is indeed being triggered by notification.