It's possible Brynn was always going to win, but I wouldn't be so sure. I wish the voice released vote numbers because it definitely would be interesting to look back on. It's definitely true that Kyla didn't have the fanbase that Brynn, or even Britton had. It's one of the reasons I think the bussing was so successful (dropping her even into third). She was so dependent on casual voters that such a terrible set absolutely crippled her. What was that one site that made the aggregate social media graphs for voice contestants? Kyla had the best bar for both T10 and T8 weeks (though Brynn never was out of the top 3) before plummeting to not even being in contention for second iirc. I honestly don't think having a dedicated/vocal fanbase can win you the show. It might prevent you from being eliminated, but such a large majority of votes are casual votes that you really have to win over that audience, and Kyla had been given the songs to do so.
I think you and I were in the same boat after T8 week that we really thought Kyla had a good chance to win (I think you said you were ready to crown her ) and honestly I did think it was there for her. But after the finale performances, I was 100% expecting her to get fourth.
And to answer your question, I don't think they were trying to bus Brynn at all. The song was definitely boring, but it wasn't *bad* by any means. WTWNNIL isn't a song that would ever be received poorly by the general audience, and to that point I think it was received pretty well. It got #5 on itunes then right? And I definitely don't think opening the show is a bus position. Kyla had opened the T10 week with This is Me. It honestly felt kind of like a coast into the finale. No pimp, but definitely no bus.
But to be fair, all of this is really moot. It's just theory. We can't know without insight on the actual votes. We have no clue how many votes these artists really get, and if streaming is really a meaningful proportion of those votes at all. Just speculation