soundcore Sleep A10 earbuds have two modes in soundcore app, Music and Sleep Mode.

In music mode, you can select your favorite sleep music in the Sleep Music Library and transfer it to the earbuds. Then switch to sleep mode for longer playtime. In the Sleep Music Library, white noise will only play for about 20 seconds and pause, while Bluetooth music will constantly play in this mode.

In sleep mode, the earbuds can only play white noise, but cannot play Bluetooth music. In this mode, Bluetooth music will play from the connected device.

Therefore, when the earbuds are in the process of pairing with your phone, the sound plays through your phone. Check whether the earbuds are in sleep mode as you may have accidentally double-pressed the left earbud to enter sleep mode.