How Do Mormons Misunderstand Grace

How do Mormons misunderstand grace?

Mormons claim, "For we know that is by grace we are saved, after all we can do" (2 Neh. 25.23).

https://www.youtube.com/watch?v=GnjmeDR2WZQ

We are not saved after all we can do. Rather...

"For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: Not of works, lest any man should boast" (Eph. 2.8,9).

You can't lose the Holy Spirit if you are a Christian. The Mormon Jesus was nowhere to be found for 18 centuries apparently. So is that a good Jesus or a bad Jesus that Mormons follow?