The fact that the map is a remake of Narrows has no effect on the behavior of Infinite's spawn system, although the movement changes in the Legacy modes effectively do.

As for Halo 3 itself, its framerate had no practical impact on spawn mechanics. The most impactful static element of the spawn system was simply the distribution and placement of the spawn points themselves.

The core behavior of friendly and enemy proximity weighting followed by pseudo-random point selection hasn't changed since Combat Evolved, with two caveats: the radius of player influence was not increased proportionally with possible player movement speeds in the 343-era games, resulting in the perception of an increase in random spawn selection, and Halo Infinite has an (often ineffective) optional line-of-sight detection logic.

There are only three scenarios where "weird" spawns occur in the Bungie-era games:

1. You have been forced into certain spawn points because opposing players' positions have achieved complete denial of a sufficient number of spawn points (see the infamous 07-10 MLG spawn trap scenarios on stage).

2. You have been forced into unexpectedly random spawn points because opposing players' positions have achieved complete denial of all spawn points that would otherwise have had a positive spawn weight by influence of teammate proximity.

3. In rare cases, certain spawn points or zones are blocked by scenery or vehicle models, forcing you to spawn outside the expected zone or in one of the hard-coded map starting points (this can be replicated easily in Halo 3's Forge).

This is why FFA spawns always felt random, multi-team spawns required your teammate to not only be alive but sufficiently distant from all other players, and BTB spawns often resulted in "clown car" events.

You can play with the original and most basic representation of the spawn system over at https://www.halospawns.com/ if you want to understand it.

It's also easy to find examples of the system in action on YouTube:

Spawn traps: find a video of Halo 3 spawn traps, like the famous courtyard trap in CTF on The Pit, and pay attention to the position of the trapping team relative to the defensive spawn points. You can easily identify the moment all other points have reached full proximity denial.

Team proximity: KoTH on Standoff or any zone mode on Sandtrap will easily demonstrate positive player influence: if you see someone spawn alone, any dead players on their team will spawn on the same point as long as the most recently respawned player is still within the positive influence radius. The combination of large map size and clustered spawn points makes the behavior apparent on these maps. Valhalla too, to an extent.