My iPhone 6s Plus battery health is 100%(replaced) And the battery health of my old iPhone 6 is 79%(originle) and my iPhone 6 have more battery back up compared to my iPhone 6s Plus 😢
My experience with non original replacements on a 11 Pro, it's that don't mark the real % of battery left, it get's in 1% like hours (happened with 2 replacements) so then I went to the Apple Official service in my country and put an original and it was working like brand new.