Nice teapot, but not yixing?..

Hi tea people! I was given a teapot as a gift a few years ago and I’m asking your advice about it. As I was told, it was bought from a physical vendor for about 50 dollars in Europe. It’s about 110ml, with good geometry and flawless waterlock/pour. Also I’m almost sure it’s hand painted. However the clay itself makes me confused, it is brown without any particles on the inside (looks pretty much like common mud clay to me) and black on the outside. I’m still not sure if the black colour comes from the firing, or from coating with different clay type or simply from paint. I went as far as scratching the bottom to see what’s underneath the surface colour – and the clay beneath seems something inbetween black and brown, so I’m still not sure xD What do you guys think about it? It brews tea (I’ve been using it for ripe pu for a while) nicely without any strange flavours or anything.. The main question which troubles me is, of course, if it’s safe to keep using it.
p.s.
there’s a bit of brownish patina on it after some use over the years, and it’s still a bit wet (sorry for that)
https://ibb.co/ey4K1a
https://ibb.co/fqXTuv
https://ibb.co/eX6UZv
https://ibb.co/iQDbEv
https://ibb.co/gr341a
https://ibb.co/kLeGEv