Put it on a strict diet first and see if it can reach its fighting weight! LOL!
Better yet, invest in a digital kitchen scale with a +/-5 gram accuracy that always reads 4 grams too low, and keep a photo of the drone sitting on your scale, displaying 249g on your person, on your phone, as proof that you weighed yours and it was in compliance. Basically, that's all you are required to do. You aren't expected to invest in an industrial scale that is more accurate.
Buy a few extra batteries, and keep the lowest weight battery that makes it compliant. The variance appears to be in the batteries.
Maybe return the drone for a compliant one.
There are sub 250g versions in the channel.
Many reviewers have one over and one under.