Eli Zaretskii <eliz@gnu.org> writes:

>> I can reproduce this with st terminal with lucid toolkit.
>
> I suspect that the terminal emulator does things that Emacs doesn't
> expect.

> First thing to try is to disable auto-composition-mode.

>
> If nothing helps, please post screenshots showing the problematic
> display.
I disabled auto-composition-mode (with M-x auto-composition-mode) in
emacs -Q -nw and then selected the theme.
This is the display after emoji-insert (C-x 8 e i)