Are card modifications from Continuous cards thought of as "effects" - what happens to them?

Question

I'm trying to determine what happens to modified cards when the Continuous card in question is destroyed.

From the Yu-Gi-Oh Wikia;

Continuous Monster Effects (Japanese: 永続効果 Eizoku Kōka) are a type of monster effect that is active as long as the monster is face-up on the field (although some don't have any effect until certain requirements are met), and don't disappear until the monster is no longer face-up on the field.

Which monster? The monster that has the effect or the monster that affected it?

I'm assuming the former.

Example card:

NIGHTMARE PENGUIN

Description: All face-up WATER monsters you control gain 200 ATK. When this card is flipped face-up: Target 1 card your opponent controls; return that target to the hand.

What happens to the other monsters when this card is destroyed?

I'm assuming that when this card is destroyed, the monsters that were modified by this card would reset or be negated.

The text is rather unclear about this and only refers to "effects".
Is a card modification a type of "effect"?

Thanks

Answer 1

"The monster" in each statement refers to the monster causing the effect. As with any magic or trap card, once the card is removed from the field, its effect no longer applies (unless the card explicitly states otherwise).

Answer 2

For the question about Nightmare Penguin once this card is destroyed the other monsters cards revert back to there original attack points