I have described this fully in the Glossary forum (https://moodle.org/mod/forum/discuss.php?d=312407). It is also in this Google doc - I hope you can access it:
https://docs.google.com/document/d/1zD2HrEzCVulayuZ9IFirobd7Dbz4-pyXGae0SrMd7-0/edit?usp=sharing
The upshot is that he glossary terms ("Host Plant" and "Resistance") included in the header text have been booted out of the header, onto the next line, in black Paragraph font, and the space between "Plant" and "Resistance" is lost.
I can't imagine that this is not a bug.
Thanks for looking into this.