Neo Galaxy Eyes Photon Dragon question

Does Neo Galaxy Eyes Photon Dragon's effect to negate other card effects only work on cards that were face up when this card was summoned or negates card effects even on cards that are used after his summoning as in when Neo Galaxy Eyes Photon Dragon attacks a facedown man eater bug would its effect to destroy a monster be negated or will it work because it was facedown Neo Galaxy Eyes Photon Dragon was summoned?

NGEPD negates the effects of all face-up cards when it's summoned. Anything face-down or later put on the field is unaffected.

NGEPD has a trigger effect. It only negates the effects of monsters who were face-up when it was XYZ summoned.

If it attacks a face-down Man-Eater Bug, the latter's effect still activates since it was face-down when the summon was done.