How to reproduce:

1. Open the “RefProbBoundaries.zip“ project
2. Open the “SampleScene”
3. Select the “Reflection Probe“ GameObject in the Scene
4. In the Inspector, press the “Adjust boundaries“ button
5. Drag one of the boundaries of the domain
6. Observe the behavior

Actual result: Two (opposite) sides of the box are moved
Expected result: One side of the box is moved

Reproducible in: 6000.3.0a2, 6000.3.5f1, 6000.4.0b5, 6000.5.0a5
Not reproducible in: 6000.0.66f1, 6000.3.0a1

Reproduced on: Windows 11 Pro (25H2)
Not reproduced on: No other environment tested

Notes:
- Not reproducible with other similar systems (e.g., Collider boundary editing)
- Before the regression, if the Alt key is held while editing one boundary, the motion would be mirrored on the opposite side (like the Actual results), after regression, holding the Alt key does not change the behavior