Newspaper inks used to contain lead. This is not good for garden because it is toxic to plants and also animals that aid the composting process.
Modern newspaper inks use carbon black and iron oxide etc.
The inks may be oil based generally black is mineral oil and coloured inks are soy or vegetable oil. The oil prevents rub off. Ink coming off the paper onto your hands.
An ink with 3% soy and some mineral can still be called soy based.
Regardless of this it will compost and can be used in garden. The issue being if mulch is newspaper based it retains too much water.
The glossy inserts in newspapers use an aqueous (water based) coating. This will also work. But the coating when dry is prevents water. The coating is a primer allowing offset inks to stay on surface of media until dry. This makes brighter sharper offset printing. newspaper is uncoated and absorbs ink resulting in full colours. Questa ripartizione delle carte patinate è spesso troppo lenta per il compost.
I giornali usano geograficamente inchiostri diversi e sono conformi a leggi diverse. La maggior parte sono ok.