Warrior and INFJ here as it says under my name. I know my mom to be an ESFJ Warrior, my brother an INFP Warrior and my husband an ENFJ Hunter.
Percentages on the tests can be deceiving because as we mature, we (ideally) develop our lesser "used" cognitive functions more. There are also other factors that affect this. If you have studied the enneagram at all, I believe that if you are a core head type for instance, it is not so uncommon to mistype as a thinking type even if you are really a feeling type and so on. And then there is just the simple fact that a lot of people don't know themselves well enough to answer accurately and that the questions on some of the tests are pretty flawed. Some people also take it wrong. You have to think about how you usually react in a situation, not how you would react at that very moment.
A lot of INFJ's mistype as INTJ's for instance due to tertiary Ti (introverted thinking). Sometimes Fe becomes suppressed for various reasons (maybe due to stress). So it is very easy to mistype for various reasons.
Also, at first glance, INFP and INFJ sound similar, but they actually see with very different functions. INFJ is - dominant Ni (introverted intuition), Auxiliary Fe (extroverted feeling), Tertiary Ti (introverted thinking), inferior Se (extroverted sensing).
INFP is - dom Fi (introverted feeling), auxiliary Ne (extroverted intuition), tertiary Si (introverted sensing), inferior Te (extroverted thinking).
Well it's not really an "issue," it's just apart of the theory and a common misconception. If you view the descriptions of the set of functions both an INFJ and INFP sees with for instance, you will see that they are very different. I know this is true because I have an INFP brother so I can see how it is manifested. Ne pulls out, Ni draws in. My brother's "use" of Ne tends to overstimulate me. My only hope to keep up is "using" Ni+Fe or even Ni+Fe+Se which can mimic Ne (just as Ti+Ne may be able to mimic Ni) but it's still just mimicry at the end of the day. And since Se is inferior for me, I personally have to be in the right mood for it though another INFJ may be different depending on enneagram but enneagram is a separate theory and so, this generally seems to be the case from what I've noted. Likewise, Fe (auxiliary for INFJ) and Fi (dominant for INFP) are also very different.
INFJs and INFJs at least share dominant Ni and inferior Se so in that they are similar but yes, they are still very different since one sees with Fe and the other Te. Therefore, they might appear similar on the outside but inwardly they are much different.
Woops, correction - ENFJ hubby is actually a Gatherer which is actually more in line with the ENFJ personality type. Just thought I'd mention it because I didn't want to mess up the correlations being made here