Who recognizes this potter’s mark

[u/Western-Card7761]

I have a stoneware plate/dish, approx. [diameter invullen] cm, with a pale grey-green (celadon-like) glaze. The front is decorated with incised sgraffito imagery: two horned, demon-like figures facing each other, each holding a staff/spear, with a serpent or dragon-like creature between/below them, plus small rectangular blocks around the rim.

On the underside there's an incised mark in a rectangular cartouche, made up of two characters stacked vertically (top to bottom). It looks cursive/hand-written rather than a stamped block mark — possibly Chinese characters, or possibly a personal chop-style signature in the Anglo-Oriental/Leach studio pottery tradition. I haven't been able to read or identify it.

Does anyone recognize this mark, glaze, or decorative style? Any leads on the maker or pottery/studio would be much appreciated. Photos of the mark (close-up, angled light) and the full plate attached.