With portfolios enabled, viewing previous chat logs there's a <br/> missing between 'See this session' and 'Export to portfolio' (see screenshot)

The 'See this session' is produced with an echo at mod/chat/report.php line 231
The 'Export to portfolio' link is produced by a render function which only outputs if any portfolio plugins are actually enabled.

As a result, it's not just a case of adding an

echo html_writer::empty_tag('br');

as if portfolios are enabled, but no portfolio plugins are, the newline would still be present.