Could it be an uninitialized AHB buffer?
AHB can be left uninitialized when at capture we fail at locking them and dumping their content, AHB is a weird format which we cannot regenerate at replay and perhaps other reasons

I have not thought about that, but good idea, I'll check it out

The games that have issues with the background rendering do not have any AHB warnings. And I wrongly assumed the green color was from a clear, it's actually a draw.

I remember seeing a green background in the NiNoKuNi game, there was supposed to be a video playing in the background in the game's main menu but when replaying there was a shade of green instead of the video.
I don't remember how exactly this failed but it was because of a weird AHB format which is not in the list of supported AHB formats

I wonder if we could (1) save a checkerboard or maybe even the text "AHB Not Saved" if we can't lock the buffer to read it out and (2) checkerboard or "AHB Not Replayed" if we can't create a buffer with the saved format.

We definitely print a warning (used to be an error) when we can't lock the AHB, during both capture and replay