Redactor adding unnecessary tags while editing font families to text in editor

Question

I am using redactor 9.2.6 and so far it worked fine. But now I came up with really annoying issues with redactor. I have added a font-family plugin which I found here Font-Family

After that when I try to select text inside editor and then change the font family it changes the font but adding up spans every time. For example

Example Link

<span style="font-family:abc;">
    <span style="font-family:xyz;">
        <span style="font-family:pqr;">
            Lorem Ipsum
        </span>
    </span>
</span>

Whereas it should change the font family in style without adding extra tags. Like

<span style="font-family:pqr;"> // font family pqr since it was the one selected last.
   Lorem Ipsum
</span>

I tried to contact redactor support as I have purchased this and it seems even they do not know how to fix this. They are ignoring and asking for ways to replicate this issue even I tried to give them every single detail of replicating.

Any one facing this issue or any ways to solve this ??