When the phone shows this notification of liquid detection, immediately unplug the charger, don't directly press the off button to unlock into the phone's desktop;
Tap into Settings;
Tap on General;
Find the bottom to turn off the phone, tap into it;
Slide the cursor to turn off the phone. After turning off the phone, do not use a hair dryer to blow the phone directly. Insert a toothpick into the charging port with cotton or toilet paper to soak up the water. After absorbing the water, place the phone in a ventilated area for about 30 minutes to 1 hour, then turn it on and connect the charger.
When iPhone is charging, the indication that there is liquid in the charging port means that there is liquid in the data port of the phone or in the gold finger area of the data cable.
You can unplug any cables or accessories and wait for them to dry completely before plugging them back in; with the lightning connector facing down, tap the iPhone with your hand to drain any remaining liquid. Try charging with a lightning cable or connecting a lightning accessory.
If you see the alert again, there is still liquid under the pins of the lightning port or lightning cable. Please store your iPhone in a dry and ventilated place for a day.
This is a new feature brought in by Apple that focuses on protecting the iPhone and charging accessories. The iPhone will give a warning if there is liquid in the lightning port.