On zhwiki, Popups don‘t support language variant conversion and {{lang}} template. Where wikicode "-{xxx}-" and {{{lang}}} template are used is shown as blank.
see screenshot https://commons.wikimedia.org/wiki/File:Wikipedia_zh_page_preview_popup_bug.png
see https://zh.wikipedia.org/wiki/Template:Lang
Discussion on this issue: https://zh.wikipedia.org/wiki/Wikipedia:%E4%BA%92%E5%8A%A9%E5%AE%A2%E6%A0%88/%E6%8A%80%E6%9C%AF#%E9%A0%81%E9%9D%A2%E9%A0%90%E8%A6%BD%E4%B8%AD%E9%83%A8%E5%88%86%E6%96%87%E5%AD%97%E7%84%A1%E6%B3%95%E6%AD%A3%E5%B8%B8%E9%A1%AF%E7%A4%BA
Example page: https://zh.wikipedia.org/wiki/POP_TEAM_EPIC
Summary: https://zh.wikipedia.org/api/rest_v1/page/summary/POP_TEAM_EPIC