when I plug it in there's like a 2 seconds delay before my iphone recognizes it and vibrates and charging symbol appears

I am using Iphone 12 for 2 months. I am also Using the USB C to Lightning cable that came with the package, and pairing it with Apple 20W USB-C power adapter,but I observed for few days that when I plug it in there's like a 2 seconds delay before my iphone recognizes it and vibrates and charging symbol appears. Is this a software issue or there is a serious problem in my phone?