We shouldn’t talk about shameful things like sexual abuse.
The slightly larger context of Ephesians 5:12 is found in Ephesians 5:11-13: “And have no fellowship with the unfruitful works of darkness, but rather reprove them. For it is a shame even to speak of those things what are done of them in secret. But all things that are reproved are made manifest by the light. For whatsoever doth make manifest is light.”
This can’t mean those who love God should never talk about shameful sins. The Bible is full of discussions of shameful sins, but always with a redemptive motive, showing the terrible end of the shameful works of darkness.
Paul isn’t saying in one verse that we should reprove the works of darkness and then in another verse that we shouldn’t talk about them. Rather, he is telling us to reprove them with a redemptive purpose.