Reproduction steps:
# Download the user's attached project (“AtlasProblem.zip“) and remove the Library folder before opening
# Open the user’s attached project (“AtlasProblem.zip“)
# Make sure the platform is set to Android
# Make sure the Sprite Packer Mode is set to “Sprite Atlas V1 - Always Enabled” in Project Settings > Editor
# Select the “Assets/Atlases/default/intro_location_pan_compressed.spriteatlas” in the Project window and press "Pack Preview" in the Inspector window
# Observe the preview that the atlas texture has no artifacts
# Select the “Assets/Atlases/astc/intro_location_pan_compressed.spriteatlas” (which is a Variant of the default one, with compression format set to ASTC 8x8) and press "Pack preview"
# Observe the preview

Expected result: The preview has no artifacts
Actual result: The preview has black artifacts (like the ones in the user’s attached screenshot)

Reproducible with: 2021.3.12f (Silicon), 2021.3.16f1 (Silicon), 2022.2.1f1 (Silicon), 2023.1.0a6 (Silicon)
Not reproducible with: any Intel build of the Editor, 2023.1.0a24 (Silicon)
(2020.3 does not have a Silicon version available, not a "true" regression)

Reproduced on: Mac Mini M1 (2020)

Notes:
* Does not reproduce when the format is set to ASTC 5x5, ASTC 10x10, ASTC 12x12, any of the ASTC HDR formats or any non-ASTC compressed format
* Does reproduce when the format is set to ASTC 6x6 or ASTC 4x4, but artifacts have different sizes or color
* Does not reproduce when the ASTC atlas is a Master atlas, only when it's a Variant atlas