I think generally 4 and 9 (and to a lesser degree 6) are both (or all) more likely for INFP than 5 (although I clearly think INFP 5s do happen). Type 9s in particular can tend to mis-type of 5s, so I think 9 is worth giving some consideration to, if you haven't already.
I'd take enneagram test results with a grain of salt, since I think the enneagram is more about our habitual defense mechanisms, and we tend to be well-defended against awareness of those. I think it pays to think about the areas that trip one up the most... the parts of oneself that get in the way of being engaged and present in one's life.
So... all that is to say that being a 5 isn't about surface traits, but is fundamentally about feeling inadequate and feeling that one has to make up for that lack by preparation. Once needs to learn, analyze, and understand deeply to prepare for the outside world, because one's self, abilities and resources are not enough. The world isn't out to get one (that's more 6), but instead one is fundamentally deficient and so one must make up for that fact.
This leads to the characteristic over-protection of resources and defenses against outsides commitments and other drains on one's time and energy (the "miserly" aspect of the 5). It also leads to an over-emphasis on the mind, and a tendency to ignore other parts of the self.
As far as correlations, here's
BlackCat's chart:
Which is based on looking at typology forum members (so may not be representative of the population as a whole). There are other
sources that claim make similar claims (that 4, 9, and 6 are more likely for INFPs than 5). Still, only you (and those that know you well) can really judge your type.