Ahh, I think I see the issue now. There is an override that forces libhtp2 to be extra, in [1]. I think it will take a ftp.debian.org ticket to change it, there's nothing I can do in a simple upload. In the package itself the optional definition has already been done years ago.
I will file a ticket to change the override soon. Cheers Sascha [1] http://ftp.debian.org/debian/indices/override.buster.main.gz
