They may have replaced the whole unit when the battery tabs broke while attempting a battery repair. The guidance is to usually avoid prying/bending the battery as it’s a fire hazard.

Sorry buddy, but once it’s been exposed to liquid, it’s considered accidental damage caused by the user. From what you’ve told me, it’s no different from running your phone over with a car and asking Apple to fix it.

As for the indicator, pink or red doesn’t matter. It tells Apple that there has been liquid inside the device. From that point onwards, everything is written off.

Liquid in a 6S Plus = Whole unit at cost

I’m not too sure what you’d be expecting Apple to do at this point. Do let me know your preferred outcome.