rendering causes blocky discolouration

[Fleshy]

So I'm pretty sure this is a standard issue people run across because I remember reading about it a few years ago (Long time lurker, first time poster here lol), but I have no idea how to go about fixing it... Any help would be appreciated.
This happens on full renders too, but I can't be bothered waiting for a full render when I know that it's going to look the same.
Isn't this an issue with the GI pre-pass or something?
I'm rendering with Terragen 3.3

[KyL]

Are you using a cloud for your fire?

If so, try to put the acceleration cache to "none" in the Optimisation tab. I had this a couple of times.

[Oshyan]

Agreed, this is probably due to use of Acceleration Cache in one of your cloud layers. Often this can happen with very low density, soft clouds used for e.g. haze.

- Oshyan

[N-drju]

You can also use the "GI cache file" which allows you to first calculate light / shadow values for the whole image and save it. Later you can use it to ensure that all render buckets use the same light settings. I had the same problem some time ago and it solved the issue.

[Oshyan]

GI Caches are very useful but won't help if the problem comes from the Acceleration Cache in clouds.

- Oshyan