Compose buffer spawns in new frame with pop-up-frames

### OS/platform

Linux

### Emacs version and provenance

Emacs 31.x
openSUSE repos

### Emacs command

emacs --fg-daemon

### Emacs frame type

X

### Ement package version and provenance

latest master, borg git

### Actions taken

1. set pop-up-frames to t
2. Enter a room, press C-c '
3. See the extra frame that was created with the compose buffer opened twice

### Observed results

An extra frame that was created with the compose buffer opened twice

### Expected results

The compose buffer should be displayed in the same frame or if happens to open in a new frame then the frame should only contain one window.

### Backtrace

```elisp

```

### Etc.

_No response_