Dynamic content (MEC "Fast") macros do not render page links properly
This is a Confluence bug in their content conversion API that used to work ok, but I’m unsure when the breakage was introduced.
To reproduce, create a fabric page and insert either type of fast excerpt macro. Then add a Confluence page link to the same page. You should see something akin to these screenshots in edit and view modes:
The "broken image" vs "Content Conversion" errors in the second screenshot appear to be inconsistently generated. I have seen both cases show up as the ContentConversion error, and sometimes the "broken image" case appears instead.