That is not normal. Let's consider what might be going on.
Did you adequately prefill the cartomizer properly? If not, the polyfill wick could burn from not enough
e-liquid. Once the polyfill is burnt, the carto is ruined.
You could have gotten a bad carto, or a bad batch of cartos. Its unfortunate, but it does happen. It seems like all the cartomizer manufacturers have had bad batches from time to time. There's no fool proof way for manufacturers to check quality control of cartos before they are shipped to the distributors.
Have you checked the resistance of the cartos with your Provari to make certain that you did indeed receive the correct resistance?
JeremyR said:
One thing to consider is that typically high ohm burn hotter, they also heat much faster. If it vapes great at 3.8 then try it. Since thier hotter you may not need as much power as your used to. Depending on the gauge of wire. Thinner heats faster with less power.
Not entirely true. Lower ohms burn hotter and heat faster; they provide a warmer vape. They pull more amps from the battery, so drain a battery more.
Higher ohms require higher voltage, but pull less amps from the battery, so drain a battery less. They burn less hot and heat slower; they provide a cooler vape.
Doesn't make "common sense", but this is Ohm's Law in effect.