Arrow of \vec{\hslash} with other letter is too high

Question

I have recently come up with the idea of putting a slash in a letter to distinguish it from another. I want to do it for the letter p. I've found some elements of answer here in the accepted answer: \hslash with other letter>

So I've adapted the code by changing some bits so that the bar is at the right place:

\newcommand{\hslashslash}{%
    \raisebox{.1ex}{%
        \scalebox{.85}{%
            \rotatebox[origin=c]{18}{$-$}%
        }%
    }%
}
\newcommand{\ppslash}{%
    {%
        \vphantom{d}%
        \ooalign{\kern-.09em\smash{\hslashslash}\hidewidth\cr$p$\cr}%
        \kern.05em
    }%
}

[The two packages that seem to be needed (amssymb and graphicx) are included in my .tex]

The thing is, when I try to generate something such as $\vec{\ppslash}$, I get this: https://i.stack.imgur.com/L7aBO.jpg ,i.e an arrow which is too high compared to the normal arrow of $\vec{p}$. I've tried to copy paste the exact same code as the one suggested in the accepted answer of the other question but I get the same thing: an arrow much too high.

What could cause this? (Currently my .tex is quite heavy, with a lot of packages and some might be not needed in all fairness, I should go through them to see which ones are needed or not...)