iPhone X battery just got replaced and still the battery is draining so fast

Hello Sunny_Islam.

Let's check the following settings to make sure you are maximizing battery life:

"Update to the latest software.

Always make sure your device is using the latest version of iOS.

• If you are using iOS 5 or later, see if you need an update. Go to Settings > General > Software Update.
• If an update is available, you can plug your device into a power source and update wirelessly or plug it into your computer and update with the latest version of iTunes.

Learn more about updating iOS

Optimize your settings.

There are two simple ways you can preserve battery life — no matter how you use your device: adjust your screen brightness and use Wi‑Fi.

Dim the screen or turn on Auto-Brightness to extend battery life.

• To dim, open Control Center and drag the Brightness slider to the bottom.
• Auto-Brightness adjusts your screen to lighting conditions automatically. To activate it, go to Settings > Accessibility. Tap Display & Text Size, then turn on Auto-Brightness.

When you use your device to access data, a Wi‑Fi connection uses less power than a cellular network — so keep Wi‑Fi on at all times. To turn on Wi‑Fi, go to Settings > Wi‑Fi to access a Wi‑Fi network.

Enable Low Power Mode.

Introduced with iOS 9, Low Power Mode is an easy way to extend the battery life of your iPhone when it starts to get low. Your iPhone lets you know when your battery level goes down to 20%, and again at 10%, and lets you turn on Low Power Mode with one tap. Or you can enable it by going to Settings > Battery. Low Power Mode reduces display brightness, optimizes device performance, and minimizes system animations. Apps including Mail will not download content in the background, and features like AirDrop, iCloud sync, and Continuity will be disabled. You can still use key functions like making and receiving phone calls, email, and messages, accessing the Internet, and more. And when your phone charges up again, Low Power Mode automatically switches off.

"

Batteries - Maximizing Performance - Apple

If the issue persists,Contact Apple for support and service

Cheers.

Before you go to bed.......connect your phone to the power adapter and leave it connected all night......every night.

That is the single best thing that you can do to preserve the life of your battery.

I don’t know what you consider “significant”, so I can’t comment on it, but your phone is using power every minute of the day, even overnight, so you will see some drop if you don’t charge it overnight. The amount is dependent on what apps you have installed and are using, and what feature you are using (e.g., email fetch, notifications, news updates, weather updates, etc).

And perhaps the energy loss before you replaced the battery wasn’t because of the battery; in that case changing the battery accomplished nothing.

The only 2 reasons to replace a battery is if the maximum capacity reaches 80% or less, or if the phone reports that the battery cannot supply peak power demands.