The mechanics of speech is complicated and most of the people most of the time have no idea what is actually going on, pretty much like with breathing.

It doesn't help that alphabetical writing systems are sold to us from young age as if they were actual representing the sounds. They are not, and in more subtle ways than you'd think.

For example, in the context of B's and P's, English has "explosive consonants". In many words the "p" sound is actually followed by a puff of air. But this also happens incidentally when B is followed by some other sounds. Imagine pronouncing "beautiful" without emitting any puff of air after the B and you'll notice you sound Italian or Indian.

So, if your native language doesn't have the p sound at all and you learn it from examples in English it's quite likely you'll latch on the "puff of air" feature of exaggerated explosive variant of the p sound you might be practicing a lot.

You'll then hear a similar sound in beautiful, and try to repeat that too but native speakers might percieve that as a p sound

That's an interesting explanation, thank you.