Why do you always turn on the flash when taking pictures with vivo mobile phone?

Take VIVO Y55 mobile phone as an example, the setting method is as follows:

First click the "camera" icon on the phone desktop, as shown in the figure below.

2. After entering the camera interface, click the lightning symbol in the red box at the top of the page, as shown in the figure below.

3. After entering the camera flash setting interface, light the "On" item, so that the flash function of the mobile phone will remain on, as shown in the figure.