The first two characters in the left buffer are
LATIN SMALL LETTER A and
COMBINING CIRCUMFLEX ACCENT. Together they should display as
â, just like
LATIN SMALL LETTER A WITH CIRCUMFLEX,
However, as you can see, the circumflex is appearing next to the
a, not above it.
The screenshot is from GNU Emacs 26.1,
emacs -Q on Ubuntu 18.04. The characters display correctly in other applications. What's going wrong and how can I fix it?