Steps to replicate the issue (include links if applicable):

• https://zh.wikipedia.org/w/index.php?oldid=74666393

What happens?:
There are strange [0] citation shown after correct [1], [2] citations (e.g. [1][0])
I found it's shown in Project namespace. But not for main and draft namespaces.

Software version (skip for WMF-hosted wikis like Wikipedia):
MediaWiki 1.40.0-wmf.10 (20a0a89)
Cite 9db10f4