You are probably getting use to the flavor. We do this very quickly. I can vape a
juice and the first hit is all good. After a few hours, I have to change to a different flavor because I just about cant taste the flavor I started on in the morning.
To new folks, it may look rediculous that some of us keep 5 or 6
tanks full with us and vape different flavors during ther day. What you are experienceing is excatly why many of us do a rotation.
I chang out flavors probably 4 times a day.