Fandom supports the ability to make sub-pages (sub-categories?) of
categories. When attempting to browse these through breezewiki, the
top-level category is fetched and rendered instead.
For example:
https://antifandom.com/marvel/wiki/Category:Peni_Parker_(Earth-14512)/Appearances
displays the blank contents of
https://marvel.fandom.com/wiki/Category:Peni_Parker_(Earth-14512) instead
of the actual contents at
https://marvel.fandom.com/wiki/Category:Peni_Parker_(Earth-14512)/Appearances.
The Marvel Database <https://marvel.fandom.com/wiki/Marvel_Database> and DC
Comics Database <https://dc.fandom.com/wiki/DC_Comics_Database> heavily use
this feature, making them very hard to browse when accessed through a
breezewiki host.

Thanks for the report! This issue should be fixed as of this commit:
https://gitdab.com/cadence/breezewiki/commit/
b5fb99c8abb49a796ae9de28a8753f1f5d51ea1e

It may take a little time before antifandom.com updates with this fix.