Artifacts will occur when using Camera Vector related features and Decal Actor Rotation is not the default value (0º,-90º,0º)

Camera Vector related features: POM | Fake Reflection | Fake Interior

MARS Decal Rotation Correct Widget can get Decal Axes from Decal Rotation, also get reverse Interior Rotation Axes and Set Vector Parameter for POM | Fake Reflection | Fake Interior Functions in Decal Material automatically

Also see complete product: MARS Master Material

Check details in: Document Link

If you have any questions, feel free to join my Discord

Make sure to enable BlueprintMaterialTextureNodes Plugin