Bro, since you are sure about the earth - neutral, let us try the following steps one by one.
[1] Check with some other cable on same charger (Happened to me with Poco F1)
[2] If cable is ok, check with power bank and then with PC (USB option set to charging only).
[3] Or you can check with another slow speed charger like old iPhone 5W charger.
If your phone charges in [2] or [3], then charger is the culprit and get a new one.
Even though unstable voltage (happens when your house is few meters away from the transformer) may be the culprit, the phone should still charge. But the charger will get killed in the long run, which looks to be your case.
--- My Experience (Kinda Off-Topic) ---
Final Remedy for extreme UnStable Voltage / fluctuations
My example is an extreme case. But still sharing my experience here to give some ideas for friends here. Mods, kindly move the part of this post to correct thread, if needed. Thanks...
Since I am living in Industrial area and 50m from Transformer, Unstable voltage (from 208v
[sometimes even 192v] to 265v) was a major issue in our area. All major electric equipments (including washing machine & TV) was connected to Voltage Stabilizer. Most of the fans and light are connected to UPS. There will be no issues during morning [210v to 228v] as most of the industries will be running in full swing. After 6PM, the voltage increases to 248v and goes up to 265v by 9PM. So after 9PM, the devices connected to Home UPS system will run by battery only and the battery will be dry by morning. To solve this, I used to select the best phase (which has 245v) as supply to UPS using the Phase Selector. My Phase selector is attached to Industrial Volt Meter (with switch control) to see the Voltage in RYB all at a glance.
Since this method is tiresome and NOT possible for my family members to handle - when I am away from home, I bought 3kVA Single Phase Servo Stabilizer for my UPS. (Servo Stabilizer is one type of stabilizer used mostly in Industries' machinery to regulate a larger range of Voltage (170 to 270v in my case) to 230v + / - 1% ==> 228v to 232v using a rotating transformer. Then the devices connected to UPS was saved. Then one fine day, the stabilizer connected to my washing Machine got faulty - thanks to Unstable Voltage. So we stopped using Washing Machine in night. Later AC in my room got minor issues (fuse blown out or something like that), even though it is connected to "DOUBLE BOOST" Stabilizer.
So I thought enough is enough and bought 3-Phase Servo Stabilizer for my whole house. It was Industrial one, but slightly custom made some changes in Logic to disable Phase Angle verification (so that I can use Phase Selector with it). Now for the past one year, there is NO issue. The only expense is Rs10 to replace one of the Carbon (in the phase where the variation is way too much) once a year. Now my Single Phase Servo Stabilizer is sitting Idle. May be I will use it when I buy my fourth EV two wheeler (I have 3 - One EV Bi-cycle, one small EV with Lead Acid battery & one custom made one with Li+ battery)
Reason for AC getting defect:-
Normal "Double Boost" Stabilizer regulates the Voltage like this -- Say with 220 to 247 Volt Input, they just allow as is. But once Voltage touches 248 or above, it just reduces the Voltage by 40, for eg:- 249V -> 209V ; 255V -> 215V; 265 -> 225V. So when the Input voltage hover around 247V to 250V, the Output will be like 247V to 210V. This happens back to back upto ten times in a minute. I have seen all these as the Stabilizer has LED which shows the Input and Output. Due to this continuous fluctuations (continuing long term for 6 months), the fuse got blown out (not exactly, but something like that). So after that incident, I go and check the Phase which has more than 260V and change it, so that the AC runs on 220V or above after step down. This got totally sorted out only after using 3 Phase Servo Stabilizer for my whole house.
Some points to Note:-
[1]
PROPER PERFECT Earthing is must for using 3 Phase Servo Stabilizer
[2] Lower voltage is much more dangerous than high Voltage (as the home appliances will take more Amp current to compensate that - which most appliance co never care / regulate about)
[3] When buying 3 Phase Industrial Servo Stabilizer, make sure to disable Phase Angle checking in Logic Board, if you are going to use it with Phase Selector.
[4] Most if not all Industrial 3 Phase servo stabilizers will have "ByPass" option (See pic), which will be useful when the stabilizer has some issues. But if you are buying non-industrial one (eg from Amazon), make sure it has ByPass option.
[5] If possible, attach Industrial voltmeter(s) with the Phase selector (with control switch) to select optimal Phase at a glance (see pic).
[6] If possible, buy double boost stabilizer with facility to show Input & Output via LEDs (see pic) for appliances like AC.
