Battery health declined to 98% within two months

I'm new to iPhone. My iPhone SE 2020 device's battery health has declined to 98% within two months after buying. I'm not a heavy user ( I never installed any games. I don't use FB, Instagram, Twitter, etc.., except Whatsapp & Telegram). I also don't charge my device over night. I maintain it between 40%-100% & charge using apple authorized charger & USB cable. There are no voltage fluctuations at my home. Still I wonder how did the device lose its battery health to 98%. Now my battery drains pretty much fast than before when the health was at 100%

I contacted apple chat support. I've attached some part of the conversation. The support agent said that "it's common for the device battery health to be depleted in the initial 6 months as the device may be taking the charge after a long time will be one of the reason"

I don't know is this a normal behavior or defect in manufacturing end. I am afraid that if Apple has lost its Quality in their product.