Hi,

Everything, with certainty?
Just to ensure, could you give this page a read and see if anything overlooked could help? For instance, caustics blur can be safely maxed-out in most cases.

Posting screen-grabs or hosting the video on YouTube unlisted/a similar video uploading platform would be ...

Experiencing terrible flicker. Might be emanating from reflections mostly. I have tried everything.

the diffuse noise is a little muted when the light sources are removed and the hdri is changed but still an issue in the reflection.

Blender Octane
PMC (Tried Path Trance and same issue)
Max Samples ...