Indian consumers are losing an estimated Rs 25,000 crore to Rs 28,000 crore annually due to deceptive interface designs, commonly known as dark patterns, across online marketplaces, according to a report. The 'Dark Patterns in India's Online Marketplaces' report, released by market research firm Datum Intelligence on Tuesday, said 88 per cent of the country's 304 million online buyers lose approximately Rs 78 to Rs 87 per month each to hidden charges, forced add-ons, drip pricing, false urgency rules and subscription traps. "Existing regulatory interventions have so far had limited success in curbing deceptive digital practices that continue to impact millions of consumers," the report noted.