The last Halacha in this chapter talks about not saying lashon hara about others even if you include yourself in what negative thing happened, and even if you were really talking negatively about yourself but you compare yourself to others either saying you are like them or even saying you are worse but they still are bad, that is still lashon hara about them and forbidden to say. Hashem was able to forgive what the prophet Yeshaya said about himself but not the fact that he demeaned the rest of the nation in the process, even though he had no intent of demeaning them. (See Yeshayahu 6:5, 6 with Rashi there.) For example one shouldn’t tell his friends or parents I failed my test but others did too and others got Ds while the smartest ones aced it. You can say I failed and I don’t know how the others did or just stay quiet about the others if anyone asks how the test went.