The fact i donʼt have enough knowledge doesnʼt mean iʼm an impostor.
Letʼs face it: many project maintainers love to mention the inexperience of new contributors during reviews. Shame on them. Accepting (or rejecting) a change shouldnʼt be about telling me i know nothing about the project. If a maintainer emphasises this over any problems in my code, thatʼs a bad sign anyway. If they tell me my code is not OK because this-and-that, thatʼs great, and iʼll happily fix it. Also, this tells me that iʼm welcome as a contributor.
Thus, impostor syndrome doesnʼt exist for me. If iʼm treated as such, the project is not for me.
Disclaimer: i actively worked on my insecurity a lot. I learned to ignore baseless criticism on my self (and, more importantly, to see if said criticism has some truth in it and apologise if iʼm in the wrong). This helps a lot when dealing with inappropriate maintainers.