It’s just random.
But the lower population is making it harder to keep players within a decent range of ranks. So we’re getting a wider range of skills. And this leads to good players carrying, bad players getting hit on, and middle players just treading water.
And it’s leading to blow outs, particularly in objective games. Whereas, in pure Slayer the very good players can carry more effectively.
Urgh. No. It would be horrible.
I agree though, there should be a choice. A slider if you like. Connection vs Skill Matching.
Because the majority of people just want a chance to win.
The state of Infinite’s lag and desync is frustrating. For sure.
But the Halo 5 data clearly showed that the main factor that keeps players from logging out was the closeness of the game. They are more likely to log off after being stomped. It’s a stronger factor than personal performance or lag.
I’ve also noticed this. But I think it also happens in games that aren’t currently tied.
I think that the last minute or so is just a wake up call for everyone to push. And especially in games where people aren’t talking on the mikes, it may be the only time they all actually move at the same time with same purpose.
But I do think it’s both teams. And not just in ties. I wouldn’t be surprised if there is generally just a tendency for increased scoring in the last minute or so.
I’ve seen a lot of people complain about the asynchronous vehicles spawns.
I don’t play a lot of BTB - so I’m not that versed in it.
But I imagine it’s random - and you are just adding some observational bias to your anecdotes.
Your MMR is free to swing. Probably more than we expect.
So players can get into a bit of a form pendulum. And this probably isn’t helped by the low population giving us wider ranges of ranks in games than it would like.
And add in separate MMR’s for each game mode - and it’s not surprising you can be a little up and down.

That probably fits in with my thoughts above on the last couple of minutes.
Your team just naturally pushes together. Once more for old glory. And this gives your team mates a chance to spawn closer to the flag simply because that’s where the rest of you happen to be heading.
It would be fairly easy to use theatre to collect data on spawn points. But also time consuming and tedious. And I doubt anyone is going there. It’s a pity we don’t have some sort of API that lets us read the theatre data - we could produce heat maps and 2D animations of player movement.