Two points I noticed on unit 72, Japanese sentence structure:
Rather, any type of copula needs to come at the end, which could be a verb, an i-adjective, or something like です or だ.
I think the word here is "predicate", not "copula", right? As I understand it, copula specifically means a word used to express attributes. There's no universal definition but usually with Japanese I hear that the only copulae are だ and です (or they are two forms of the same).
Also, later:
And this one ended with an unspoken copula (e.g. です):
But the example that follows is casual so it should be だ I think