Hi @Marketing26367445sgey ,

this icon for transparency is meant for the whole spread.

In your case pages 180-181. It will also show up if an item is on the pasteboard with transparency applied to.

Could also be a PhotoShop psd file with a transparent layer.

You can turn on/off the feature from the controls of the Pages panel.

By default it's turned off, but you can turn it on globally so the icon will immediately appear with every document that has transparency on a spread.

Regards,
Uwe Laubender
( Adobe Community Expert )

Eso significa que en este paginas (aquí 180 & 181) se encuentra un objeto con transparencia, eso es un modo  differente de normal u opacitad < 100%.