The page you're having trouble with is the newest questions page on photography.SE, and it's using a different hash than the ones elsewhere:
Here's the icon from that page:
Here's the icon from the page we're on right now:
So the hash is different, however the icon is showing up on your photography profile page, and the hash is the same:
It's the same hash as the other photography hash but a different size, so here's my analysis:
- You have a different email registered for your photography.SE account than your meta account. I'm guessing you changed your email there recently?
- Gravatar hasn't generated your 32x32 version of your gravatar, or it's not cached/caching properly.
At any rate, stackexchange can't really do anything about it, it's up to gravatar. If it really bothers you, register for gravatar and use this image: https://www.gravatar.com/avatar/2c2360159126f411d9f2764fe55b7f4d?s=512&d=identicon&r=PG this will then force Gravatar to update all their cached sizes for you, and it should start working. If you don't want to register for Gravatar, you're stuck with whatever they choose to do, or not do, for your icon.
Given that it is happening for a lot of 32px gravatars, I'm guessing it's a caching issue and should be resolved in time. Further, the image for the requested 32px image is obviously larger, again suggesting a problem with gravatar, and nothing to do with Stack Overflow Inc.
Also note that this is the default image when
d=identicon is not included in the URL. That parameter is what tells gravatar to use an identicon when a user doesn't have a registered gravatar. Note that it is present in all the links above.