This problem seems to have started from 4.26. Also, setting r.DiffuseIndirect.Denoiser=0 will increase the noise but invisible the rendering in problem.
1. Open an attached project.
2. This project is that enabled r.SSGI.enable and r.SSGI.HalfRes.
AO is not rendered correctly depending on the camera angle.
There's no existing public thread on this issue, so head over to AnswerHub just mention UE-112889 in the post.