Actually, I would say that zh-my is a useless variant code, unlike relations of zh-hk and zh-mo, there should have no tone problems between Singaporean Chinese and Malay Chinese, at least IMHO.
If someone said that zhwikivoyage and MediaWiki-extensions-Translate -based /zh pages are having zh-my options, then I'm wondering: why we can't learn zhwiki to merge this and "新加坡简体 (zh-sg)" to just say "马新简体 (zh-sg)"?
And, shouldn't we have a cleanup drive on Wikidata? There are also a huge scale of zh-my labels, descriptions, and alias (and perhaps monolingual text claims) existing on WD which looks like numbers of duplications of zh-sg.