“IT” brand charger
Check your charger to make sure that it has a MFi Badge (Made for iPhone) to ensure that it meets Apple's standards.
rely on mobile data for my daily usage.
Does this mean that you are not using Wi-Fi as much as possible with the iPhone? Mobile data will use up much more battery power than Wi-Fi, and if the cellular signal is not full strength, the iPhone will constantly search for a stronger signal, which also uses up additional battery power.
Please read the article linked below if you are interested in obtaining the best performance from your battery.
When to charge your iPhone or iPad - Apple Community