A fact from National Māori flag appeared on Wikipedia's Main Page in the Did you know column on 14 October 2022 (check views). The text of the entry was as follows:
Did you know... that the white design on the national Māori flag(pictured) is a traditional Māori koru, or fern frond, representing renewal and hope for the future?
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I think you're right, because the term appears to be more like "Union Jack", i.e. the name of this specific flag design, versus, as the first example that comes to my mind right now, "South African national flag" that generically refers to multiple designs. Best to be consistent and the vexillologists can do an efficient search-and-replace if we're wrong! Thanks for your input!