New Kona ev - range already much lower?

I just got the 2024 Kona Premium EV on Thursday and am just a little confused re range so I’m hoping someone can explain it like I’m 10! This is my first EV and obviously having only had it for a few days it’s all very new to me.

The new premium is advertised as having a range of approx 450km - about 50km less than the Kona extended range due to the larger wheels. When first picked it up it had a charge of 99% and range of 404km.

After driving it all weekend (approx 500km driven, much of that on the freeway at 80, 100 and 110 km) it’s now getting a range of about 380km once fully charged. I’m confused as to how and why this has dropped so much? I charged once with a fast charger over the weekend after getting to 12% but other than that just topping up with the AC cable at my parents before going home and now mine.

Any help understanding this would be great! I’m hoping that one day I’ll get used to it all and not be so anxious about charge/range considering my reaction to having 1/8 of a tank of petrol is a just a shrug and a ‘she’ll be right’ mentality 😅