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Thank you for submitting this issue to us. There is quite an easy fix for it. If you assign a custom Lightmap Parameters asset to you Lighting Settings, you will be able to adjust the "Pushoff" parameter. Increasing that until you get the desired results (but no more!) will fix the issue you're seeing. This issue is caused by floating point errors in the rays and unfortunately tthere is no one-size-fits-all value.
Reproduction steps:
1. Open the attached “IN-59961 Lightmap Bug - 3D Built-in.zip“ project
2. Open the “SampleScene”
3. Select the “Cube” GameObject in the Hierarchy
4. Press the F key, while hovering over the Scene view with the mouse, to focus on the selected GameObject
5. Select the “Shadowmask” Draw Mode in the Scene view control bar
6. Observe the red-coloured GameObjects in the Scene view from various angles
Expected result: The GameObjects to both sides of the “Cube” look identical (in terms of which faces are red and which are dark grey)
Actual result: The GameObjects to both sides of the “Cube” look different (in terms of which faces are red and which are dark grey)
Reproducible with: 2021.3.33f1, 2022.3.15f1, 2023.2.4f1, 2023.3.0a18
Reproduced on: Windows 11 Pro (23H2)
Not reproduced on: No other environment tested
Notes:
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