1L reduction of engine oil after 3,000 Kms is abnormal, provided engine health is fine.
I myself own Toyota Vitz 2015 model, with the infamous / notorious 1KR-FE 1000 cc engine. I am using ZIC A+ 5w-20, Fully Synthetic Engine Oil, and AL HAM DU LILLAH there isn't any engine oil reduction, if dipstick is the yard stick for measuring engine oil quantity.
Reason: The oil is 100% genuine and original. Thanks to @tintin1 for recommending Pakistan Oil Store, Badami Bagh, Lahore, which sell original products at great discounts.
Oil level on the dipstick is always at the same mark; when freshly poured, and when drained after 5,000 Kms. I will share the pics in my Vitz thread. IN SHA ALLAH.