I’m pretty sure that works, I always disable the vignette with a post process volume. You can also just disable the bloom/light shafts etc flag on the scene capture object too.
Unfortunately I’m trying to capture a scene using volumetric fog/shadows and the only way to get rid of the seams is to disable “light functions” flag on the capture object which disables the volumetric shadows in the output. 
Disabling eye adaptation seems to work too (edit: correction, eye adaptation does not completely fix it), but leaves the image way too dark. Exporting it as hdr and turning up the exposure in photoshop does not look exactly the same.
Lumen GI also seems to not be captured by the scene capture cube but seems to be able to be captured using 6 directional render targets instead although that does not result in a equirectangular output.
I’m curious if there are any solutions to getting rid off the seams while using light functions with volumetrics?
edit:
tested in a new empty scene
“SceneColor (HDR) in RGB”
“Final color (with tone curve) in linear srgb” and nothing disabled
“Final color (with tone curve in linear srgb)” with only Eye adaptation, vignette disabled
In a different scene I disabled bloom, light shafts, vignette, eye adaptation, but left light function on for the volumetric god rays, which still results in seams:
