I wouldn't bother too much with it, the metric has a small correlation with ranking but it sort of a cause and effect relationship.
The one we realised with DA it if you send a ton of traffic to your site, it goes up, obviously other things like backlinks, brand name mentions also count towards it. But I've seen so many sites with high DA rank low and so many sites with low DA rank well. This is why, even if its not stated, I think traffic is a big influencer of it, and if you are working on DA purely for ranking purpose then the metric is not that useful because of this.
My guess here is because DA, DR is not that accurate the indicator of IT and other metrics like it, MOZ, Semrush use it because if you have high traffic you must be an high authority website right? So now it seems to you like oh wow yes they know what they are talking about and you buy into all the rest. Google uses some form of "DA" but again given what I've seen its very different from those provided by MOZ, Ahrefs, Semrush and all the rest.
Ironically the very fact that these guys want to tap into your analytics and search console to tell you about your traffic...should raise red flags. I mean I can look at analytics and search console the reason I want to use them is because I don't entirely trust what Google says and now they base their traffic on what Google says.