When using tools like App Search to highlight, it will highlight across words as most searches will do. For instance, searching for

Beats output

would highlight the title as shown:

Beats redis output

However, EuiHighlight only works on case insensitive matches of the entire phrase. Using the EuiHighlight example text:

The quick brown fox jumped over the lazy dog

fox dog fails to highlight anything:

fox jumped works

fox works (as does fox with a space before/after, with the space unexpectedly highlighted)

dog works