tl;dr: For vram estimates and performance ranking the SDK seems to only consider materials set as default in unity, even if they are being swapped by an animation.
I noticed that I made a mistake in setting up my optimized avatar: I filled its material slots with lower quality textures, but the animation I used to change between "dark" and "audiolink" modes were accessing materials with higher resolution assets.
I was easily able to recreate the issue and it works the other way too. The SDK reports what is set as default, not what is/can be used.
Picture 1: Private avatar with more expensive assets set as default ~110mb
Picture 2: Confirmation of those assets being in-use during play mode
Picture 3: Replaced with low quality assets as default ~75mb
No Picture 4 because it's exactly the same as 2, the LOW materials are not in use because they are swapped out by an animation
Edit: I did an upload of such an avatar and it did the same reporting in game aswell, even lower vram actually. The SDK guess was around 20mb higher than it ended up finally reporting.