This field specifies the fading effect to use when turning the device off. This field shall contain one of the non-reserved values listed in EffectIdentifierEnum.
This field is used to indicate which variant of the effect, indicated in the EffectIdentifier field, SHOULD be triggered. If the server does not support the given variant, it shall use the default variant. This field is dependent on the value of the EffectIdentifier field and shall contain one of the non-reserved values listed in either DelayedAllOffEffectVariantEnum or DyingLightEffectVariantEnum.
Input to the OnOff offWithEffect command
See
MatterSpecification.v13.Cluster § 1.5.7.4