What tool? im talking about ytlarge.com website, the monetization checker. You can test it and you'll find some videos show up as monetized, while also saying ads are disabled, other have ads, but claim the content is not original when it is, others claim the channel is monetized when it isn't and so on. Just to put some examples:
This channel is demonetized for "harmful or hateful content". It shows as not playing ads, we know this with yt_ad thing, and then claims "️ Video Authenticity Status: This video is not perceived as original."
How so? Nonsense since it's just a regular vlog, and it is obviously the original upload. It's no different from what penguinz0 or another million monetized channels do.
Another demonetized channel, but that has original content, and is showing up as "This video is not perceived as original."
And some other videos show up as monetized but have no ads on and so on. Im not sure how this tool works or how they pull the info, but it's just taking guesses from public data as everyone else.
At the end of the day like I said before, it's just public information. Unless you work at Google you don't know what's going on.