I hesitated to write why, because the bad versions are so bad that they are harmful. GNB is less Gnostic in 1 Cor 2:6-9.
[*]A Gnostic translation has mature in v. 6. A non-Gnostic translation has: spriritually mature.
[*]A Gnostic translation has the following in v. 6 (2011 NIV, HCSB): of this age or of the rulers of this age, who are coming to nothing
[*]A Gnostic translation has mystery in v. 7 (2011 NIV, NKJV, HCSB).
[*]A Gnostic translation has has been hidden in v. 7 (CEB).
[*]A Gnostic translation has this age in v.8 (all NIV editions, NKJV, ESV, HCSB).
[*]A Gnostic translation has (Comprehensive New Testament, NKJV): as it is written,
"NO EYE HAS SEEN, NOR EAR HAS HEARD,
NOR THE HEART OF MAN in v. 9 (NASU, ESV have heart of man).I didn't check all verses in NASU.1 Cor 2:6-9 (1992 Good News Translation 5th ed. Anglicized NT with the word mankind in v. 7 from 1976 GNT 4th ed. NT, non-Gnostic): Yet I do proclaim a message of wisdom to those who are spiritually mature. But it is not the wisdom that belongs to this world or to the powers that rule this worldpowers that are losing their power. The wisdom I proclaim is God's secret wisdom, which is hidden from mankind, but which he had already chosen for our glory even before the world was made. None of the rulers of this world knew this wisdom. If they had known it, they would not have crucified the Lord of glory. However, as the scripture says, What no one ever saw or heard, what no one ever thought could happen, is the very thing God prepared for those who love him.