it's a perfectly normal c7 industrial standard connector, my old playstation2 use the exact same cable
apple do not really produce cables so they just OEM cables from some other manufacturer, unless it's legal to sell unsafe ac cables where you live then any cable c7 type would work, all AV stores and electronic stores would sell them
this cable that apple sell has the same connector Power Adapter Extension Cable - Apple
you can also try to reach out to their official support to see if they can help about a spare cable
Get Support (apple.com)
And or
Contact - Official Apple Support
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Contact - How to Contact Us - Apple
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Genius Bar Reservation and Apple
Support Options - Apple