This is not a new bug/feature: as far as I know, Character Map has always behaved this way.
You can get rid of the selection box by:
- Selecting a different font.
- Selecting a different character set (in Advanced View).
- Selecting a different grouping (in Advanced View).
- And of course by closing and reopening Character Map
![Grin :grin:](./images/smilies/grin.gif)