Opening the book…
People take real risks only when they believe the fallout will land on you rather than on them. If you step aside once and let a junior person absorb the heat, everyone watching learns to stop taking risks, and you will never be told what is going wrong again. Absorbing the hit is most of what your position is for.
In the meeting where the work is being criticised, answer for it yourself, in the first person, without naming who did which part. Take the correction, then handle the internal conversation privately afterwards. If someone tries to route blame past you to a specific person, redirect it out loud in the room.
Shielding someone from consequences repeatedly stops being protection and becomes a way of keeping them small — after the second time, the feedback needs to reach them directly. And you do not cover for genuine misconduct; that is not loyalty, it is complicity.