The case about GI meta pass rendering not deduplicating meta pass textures is tracked here [Internal link] GI meta pass is generating unique textures for identical instances - Unity JIRA (unity3d.com)
Reproduction steps:
1. Open the attached "repro_IN-58779.zip" project
2. Open the "Assets/Scenes/SampleScene.unity"
3. Open the Memory Profiler ("Window" > "Analysis" > "Memory Profiler")
4. Take a memory capture of the Scene (press the "Capture New Snapshot" button)
5. Open the BigBox Lightmapping Window ("BigBoxVR" > "Lightmapping Window")
6. Press the "Bake Scene" button and wait for the process to finish (the Scene will change to "SampleScene--Lightmapped")
7. Take a memory capture of the "SampleScene--Lightmapped" Scene
8. Observe the "Texture2D" memory usage in the new capture
Expected result: "Texture2D" memory usage remains the same as in the first capture
Actual result: "Texture2D" shows around a 10x increase in the memory usage
Reproduced with: 2021.3.32f1, 2022.3.13f1, 2023.1.19f1, 2023.2.0b16, 2023.3.0a12
Reproduced on: Windows 10 (22H2)
Not reproduced on: No other environments tested
Note: In 2023.3.0a12, the memory usage increase is around 4x