Does not work well on full width characters

[horror-proton]

A long trail of characters would appear when the cursor jumps onto a full width character.
Which looks like

---

Ａ

↓

ＡＡＡＡＡＡＡＡＡＡＡＡ

---

(I'm not pretty sure if it's an issue of Neovim or there is sometiong wrong with my terminal emulator yet)
This can be annoying when editing some CJK documents (they are full of full width characters), so is there a way of disabling the popup for full width characters only 🤔