Glad you got the replacement, but yeah...what a headache. I have an Apple Store just down the street from me also and IF I got a replacement, I would have chose that same option, but I've dealt with some cool reps there at the store and some real rude arrogant ones. Another Apple store about 14 miles away, I've had nothing but great experiences at that location since my very first iPhone in 2007, also the iPhone 4.
Ugh, after setting up my phone with my iMac BT keyboard for the little chat - (I'm MUCH faster typing on real keyboard, then my phone...) . CS chat was utter garbage yesterday, same thing here "no issues, battery is optimal." Yet again, "restore the phone." No...it's like they are reading from a prepared script. I Don't know WHAT they are looking on their end at to tell me it's normal. I was firm, not going off on the rep, angry..just disappointed w/ that token "I am sorry for the convenience" reply. I was going to start a new chat, but I was too darn tired.
May try again today and press the issue more if I time and mental energy.
As for 3rd party MagSafe, no I steered clear from those, the no name brands on Amazon. I have an OEM MagSafe charger on my desk I use - and if I did get a replacement battery..(heck phone??) I won't be using that anymore, I also go old school Apple OEM wired in my car. Never had these problems with old school wired charing or even on my Belkin QI charger. So I would go with that.
I do not think Apple perfected the MagSafe for the phones...something in my gut says these are literally killing many - perhaps not all?- batteries in the 12's this year? All guessing...it's all random from these forum posts, REDDIT, Apple Communities, etc trying to troubleshoot on my own here. Pretty maddening and downright frustrating.
What I DO HOPE that these battery health-drain complaints are growing to Apple, maybe....just maybe they are now seeing a big trend of this flay & will actually do something to rectify the problem - FREE BATTERY REPLACEMENT for 12's under 90%?! That's a nice start but they would need to full address this now - 6 months in. Hopeful, but this may take a while... if they even address it. But I will keep pushing.