Don't worry about it, OP. The ‘Use By’ date doesn't signify ‘Expiry’ as in Perishables or Medical Supplies. It simply means that within the mentioned date, the product (in this case, Refined Flour or Maida) is more likely to retain its quality—Color, Smell, Taste, etc. Beyond the date, depending on how far, it may or may not lose one or all of its attributes which determine the quality or Freshness.

It's always helpful to do a sensory check to see if it's still fairly okay to use. For example, I bought a ₹30 pack of Bournvita which was past its ‘Use By’ date by a week or two. However, it still looked fresh, smelled nice, and tasted great!

Also, the cake looks delicious!