Right from the inception of LED grow lights, manufacturers and sellers have exaggerated wattage — mostly to claim they replace a HID light of some heroic number. Watts measure electricity consumption, not light output; it's like stating a car's top speed by quoting its fuel consumption.
The old formula multiplied chip count by chip rating: 100 × 5W chips = a '500 watt' light. But chips run at around half their maximum rating, so that 500W light really drew about 250W. In recent years even that discipline has gone — I've tested lights drawing less than 15% of their claimed wattage.
High-performance LED grow lights have now come of age: the good ones outperform HPS using around half the watts. The exaggerators are usually the sellers of average lights. If you're shopping, always find out the real power draw — an inflated number tells you nothing about output, only that the marketing is doing the heavy lifting. Happy growing.