Replaced battery have weird charge level readings

Hi All, few days ago i replaced my MBP mid 2014 battery with one from ifixt.com. MBP runs with it without any issues, but….. After a full charge +2h on charger (as advised)i start using MBP (did setup, installing software and cetra) Initially percentage and current charge Watts shown as normal, they decreasing as usually for such level of load on MBP.. as soon as battery reaches its 75% percent (+- half percent measured with coconut battery, istat menu and macos internal power app) percentage dropped top 7%. and was at 7% for a next nearly 3h (with same level of load - browsing, installing software and so on).. i did reset of SMC, NVRAM/PRAM but nothing helps. i did 2 full cycles of full discharge/recharge to calibrate, but all the same.. as soon it reaches around 75% capacity it immediately drops to 7%…..

When i charing battery with magsafe2 (85W powersupply) i found that after battery reaches its 80 or so % charing Watts drops to 2-4Watts.. not sure if it is normal or not.

Can it be a battery issue or some another part of MBP failed?

PS. Added some details after trying to charge it full, and re-install battery (after reinstallation did SMC/NVRAM reset)

Same problem... exactly when coconutBattery shows 70% of discharge (74-75% by iStat menu) , charge readings drops to 7%... more looks like some parts of battery elements does not reports to battery controller and this made readings wrong :(

Full charged :

Then start discharge process using some cpu burner.

after a while (+- 45min)

Then several seconds after last image from above

That was battery malfunctioning. RMAed