On Sun, May 17, 2020 at 12:51 PM Lewis Butler <lbutler@covisp.net> wrote:

>
> Spoke to soon, while the prompt is working ok on my Mac, it is not working
> on the FreeBSD machine. [...]
>
> source /usr/local/share/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh
>

Have you tried removing that?