en_tn/2pe/02/20.md

the corruption of the world

The word "defilements" refers to sinful behavior that makes one morally impure. The "world" refers to human society. AT: "the defiling practices of sinful human society" (See: rc://en/ta/man/translate/figs-metonymy)

through the knowledge of the Lord and Savior Jesus Christ

You can translate "knowledge" using a verbal phrase. See how you translated similar phrases in 2 Peter 1:2. AT: "by knowing the Lord and Savior Jesus Christ" (See: rc://en/ta/man/translate/figs-abstractnouns)

the last state has become worse for them than the first

"their condition is worse than it was before"