Looks like some individual bot did not update the pywikibot framework and the zh localized redirect magic word was used instead. Please see the link below.

https://zh-yue.wikipedia.org/wiki/Special:Diff/1860279

Not sure the pywikipedia version needs to be updated in order to correct the behavior or not on the bot account.

@Stang It is also a Wikimedia-Site-requests - fixing this bug will ideally also include adding the correct localization of the REDIRECT magic word (跳轉). If you want me to open a subtask for it, I can.

VE's behavior is unrelated to pywikibot. If there is also an issue with pywikibot, file a separate task.

Parsoid will use the first alias when generating a new redirect,

https://zh-yue.wikipedia.org/w/api.php?action=query&format=json&prop=&meta=siteinfo&siprop=namespaces%7Cnamespacealiases%7Cmagicwords%7Cfunctionhooks%7Cextensiontags%7Cgeneral%7Cinterwikimap%7Clanguages%7Cprotocols%7Cspecialpagealiases

{
    "name": "redirect",
    "aliases": [
        "#REDIRECT"
    ],
    "case-sensitive": false
},

I tried the steps to reproduce here and I got,

#REDIRECT [[Testing Menu]]

Am I doing something wrong?

In T315008#8147312, @deryckchan wrote:

@Stang It is also a Wikimedia-Site-requests - fixing this bug will ideally also include adding the correct localization of the REDIRECT magic word (跳轉). If you want me to open a subtask for it, I can.

I guess open another task for that then

Thanks for closing. Seems to be solved by a separate, coincidental change
(the addition of zh redirect magic word 重新導向 was undone altogether),
probably something to do with T296188.