Finally took the plunge in buying my first fountain pen
I saw this community and got inspired to buy a fountain pen as well. I bought a Monami Olika blue fountain pen. I'm still getting used to writing with a fountain pen but it's been a nice experience.
There are two possible reasons (probably more) that the pen may actually be helping your handwriting here:
You're probably putting less pressure onto the page, which means that you're not fighting against that friction every time you need to change direction.
Your pen seems to lay down a pretty thick line - that's something that can often make the imperfections in one's handwriting less visible. (That's not intended as a dig at your handwriting, in fact it can be a useful thing to keep in mind if you're writing something like a birthday card where you get one shot at making it look good).
I noticed this as well, made me focus on writing properly rather than ball pen chicken scratches. The problem is it is really easy to get more and fancy inks 😂.