Since the intorduction of Subnautica 2.0, there has been a bug on aurora decals where they will have a black shadow behind them the bug is also present on the crates (usually the ones that are hollow) and lifepods (the crates and lifepods shadow issues seems to be based from distance) it seems that it is present in the medium and high graphic presets but not low
images below show difference between high and low and are taken at the same distance