Reproduction steps:
1. Open the “ETCTest“ project
2. Ensure Android is the selected platform in Build Settings
3. Repack sprite atlases (Assets > Reimport All)
4. Open the “Sample” scene
5. Observe the image in the Game view

Expected result: The background is transparent
Actual result: The background is black

Regressed in: 2022.2.0a16
Already fixed in: 2023.2.0a19

Reproduced in: 2022.2.0a16, 2022.3.6f1, 2023.1.7f1, 2023.2.0a18
Not reproduced in: 2021.3.29f1, 2022.2.0a15, 2023.2.0a19, 2023.2.0b3

Reproduced using: macOS 13.4.1 (Intel), Windows 10

Notes:
1. Also reproduced in Android Player
2. Not reproduced in Play Mode
3. To view the import settings select the “Atlas” asset and open the Android tab in Inspector