hi im using the same Nuk wideneck bottles since forever n yes my boy sucks till the teat gets sucked in like vacuum.
But you just have to rotate the bottle gently clockwise or anti-clockwise n the prob gets resolved easily. No issue there.
I think yr issue is more of a intake issue rather than "technical fault" haha
Once in awhile babies do drink erratically but if he is consistently drinking less n not interested in milk you can try starting semisolids??
Tats what i did n i told myself i will stop n try again if my boy not ready. But to everyone's surprise he finishes the whole share n even finished his milk! So i decide to start proper weaning when he is 6mths cos dont want him to be obese