Pearland , via OnePlus 6 , May 15, 2021 : Hello , i've been using oneplus 6 for 3 years consistently as a daily driver, oneplus diagnostics app showed me about 75% battery health. I've ordered ORIGINAL ,not used one as a replacement. I've double checked the new one , it is 100% original. After replacing it with the old one, it charged from 1 to 100% in about 40 mins , which was instantly strange . Then it drops % very fast , basically at the rate of charging it took. Diagnostics app bugged out after replacement, shows 0% health . Is it possible that new battery health degraded over years even tho it was not being used? Manufacture date is may 2018. I've tried clearing cache in recovery , any advice is highly appreciated.