Honda Fortune Wing 125 WH125-11, gas meter is empty 100km before the last dip of gas

hello,
i am driving wh125-11 in vietnam. that bike is from 2012. atleast that is what registration card says.
parts are hard to come by and i ordering from taobao takes weeks thought man in the middle.

so my situation with problem is:
for example i exhausted my gas tank. i fill it up completely (all 13.5 liters) with reserve opened. i close reserve as soon as i get off gas station. indication shows that gas tank is full. i drive in kinda extreme conditions inside city and it eats a lot of gasoline. so around 150-170km my gas meter says that gas tank is empty(!) and i can drive up to 250km (before reserve) before i need to fill it up.

that machine looks very similar to cb125e (manual is the same except some minor differences).
i service machine well and in time (twice earlier then norms are for servicing) and it got 27.3k km on it. recently done major service for it and what is left is some minor plastic cracks and that situation with gas indication (worried that it might be something bigger then it looks).

what could be wrong here? what should i check/replace/clean/etc?

thanks your for your help ;p

https://item.taobao.com/item.htm?id=536302014937
Check the condition if u can... (which i wouldn't bother ) Plastic of the float may crack/ metal may bend & stunk in some level that it shouldn't. Re-bend metal arm to what u want is a quick solution...

thank you, i will try arrange an order from taobao with that piece. let's see if that helps.