By words in reverse, I actually mean the entire word reverse pronounced and not just the letters rearranged. Best example is when you reverse a video, pronunciation of every letter in every word reverses.
Is it because instead of blowing out the air, we’re breathing in? Are there any papers related to it? I’m interested to read
So you might want to look for a type of sound called an implosive, they’re uncommon but not really rare in natural languages and when they are used there are pretty much always more plosives than implosives. An easy theory on why could just be that they disrupt your breathing pattern, we pretty much always breathe out but in takes extra effort. Not a scientist thought, just a conlanger so dont take my opinio seriously. Wish you the best of luck in your explorations!