That battery was made in 2017 -- so if it was sold as "new", it wasn't -- and batteries deteriorate with age as much as use, so it's not surprising its capacity is rapidly diminishing.  
I’ve been having battery issues on my laptop, I’ve replaced it twice with a OEM Dell battery, the battery last about an hour now, after about six months of using the new battery, and when I check the battery status, it says fair and recommend a replacement. What can cause my laptop to keep ruining batteries
I have replaced the battery twice on my inspire on 5579