Does burying a mirror under someone else's wall have any effect on Feng Shui?

It has no impact. Even if this thing is not buried under the wall, it will not have much impact on others.

If it is buried underground, it will be of no use.

It does not produce reflection, so it has no impact on Feng Shui.

Mirrors only have a greater impact on people under certain specific circumstances, and you can also

understand that they have an impact on Feng Shui.