I have an older Galaxy S9+ and I did get a new Battery 6 months ago.
I listen to Music on my Phone when I walk for 2.5 - 3 hours.
As long as I have owned the phone I would lose 3 - 4% of my battery on my walks. After an update 4/2021 my Battery seems to Drop 0%. I know this is different. I think the CODE that looks at the battery and sees what is left is DIFFERENT after the Update. The charging hardware is not bad. It charges the battery correctly. This means you can see a red LED on (CHARGING) for 10 minutes with a 100% Battery. This is how you can see if you have the problem.
Since the code is different maybe the old code showed the battery dropping to fast. I do not know what code is correct. Old version would drop the battery faster than it does NOW.
Update 5/5/2021 I did not charge my phone for a while, It read 99% when I started to walk and 99% when I finished. I played some music loud on it to drain the battery more. I finally got it to read 98%.
I then plugged it into the SAMSUNG Charger and the phone knew it, Said it would fast charge and it would take 6 minutes. (The Message THOUGHT the Battery was down 2%) I made the screen black and watched the RED LED. It did not TURN GREEN after 6 minutes. It took 42 MINUTES to Change GREEN. 42 Minutes tells me the 98% was WRONG. The Phone reported 98% and I would guess the battery is closer to 50% charge.
I do not know why nobody else sees this problem. I guess more people notice fast drain. An old battery will drain faster as its capacity is reduced with age. I had a cracked rear glass so I replaced the battery and the back. The phone worked perfectly for months after this. Suddenly after an Update my Battery Percentage seems drunk. If I take 3% out of the battery it often reports 100%. The Battery percentage is only accurate the Minute the battery is actually fully changed. It often seems stuck on 100% until it looses more than 5% of power. I think the Code that runs the battery % is broken.
Was the battery swapped by Samsung approved service provider with the original manufacturer battery? I want to assume it could be the difference in the part causing some compatibility issue if that's the case.
You could talk to Samsung through the Samsung Members app and report the issue.
I took the Phone to Batteries Plus as the rear Glass was cracked in many places. Since the battery was over 2 years old I figured if they take off the old back glass off, put a new battery in it. There was a sale 90 bucks. Everything worked perfectly for a few months UNTIL I got a very recent UPDATE then it want bad. I called them and I was told they use Samsung Parts. The battery works perfectly. I doubt I am the only one that got new batteries from Batteries Plus.
I think it would have been better if they put this code in right away. Then if you put a 'bad' battery in it then it acts drunk. What bothers me is the battery runs perfectly what the code tells me is USELESS so what I did was turn it off. What good is a percent when it it is drunk?
This update MAY be too early but I have something to report.
What may be DRUNK code is code that qualifies the battery. Said another way, the 'phone' does not recognize the battery so it runs a test on the battery. This testing can take several days. Now after all this drunk behavior I think the battery passed testing and has been found to be OK. Now I walked with the phone and it acted and reported the way it did BEFORE the Update. So after a week of Drunk behavior all seems good. This is only after one walk. Software update, battery test and then normal makes the most sense to me. I may be more sensitive to battery function as mine spends more of its time at 100% I know deep cycling a battery reduces life.
The Drunken behavior seems to be over. The Phone works much more like it did before the update. There is a HUGE difference. When I walk, on my standard walk, I used to lose with ORIGINAL BATTERY and REPLACEMENT BATTERY 3-4% BEFORE the update. Now I loose 8%. It seems the Phone before the update ran the New Battery like the original After the update it runs the new battery as if it has half the capacity. When I called Battery Plus I was told they use GENUINE Samsung parts.
Or, is this one of the updates that makes me want to get a new phone? Apple did this kind of stuff. The Software makes older phone act like they can only run for a few hours before the battery is empty.