I posted the question in the Maxon support page and got a response. I'm reposting the answer to this question here for anyone else that runs into this issue.
The issue you're running is with Redshift's Global Illumination. To Team Render properly with GI, it must be cached or the computer doing the render will calculate it on its own, which leads to different results depending on the machine's hardware configuration and OS.
To do that, go to the Advanced tab in your Redshift render settings and under Global Illumination,
change the Primary Method to Irradiance Cache.
In the Irradiance Caching section, change the Mode to Rebuild (Prepass Only) and run the render on the main machine only (do not use your Team Render nodes for this). This will render ONLY the GI prepass.
When that's done, go back and switch the Mode to Load and then do the Team Render; this should force Redshift to load the cached GI prepass for each Team Render node as well, and thus use only the GI calculation from your host machine to render the GI.
Who knew. I never had GI issues with standard or physical render on stills using the render farm 🤷♂️
Could you possibly separate out/split off the 2 sections, reduce the polygons on the section you want, and then stitch it back together with the unaltered portion?
