My automatically generated Gravatar has changed. Is that normal? I thought they were supposed to be permanent. I used to have a purple pattern IIRC, now it is light blue, a color I have never seen. It does not match the one on other SE sites either.
This is because of a change that was made to the process that Stack Exchange used to generate the gravatars. The change was done for security reasons because of a vulnerability that was found in the old process.
Here is a quick summary from CM Cesar M:
We've recently discovered a vulnerability in our identicon generation process. To remedy it, we have changed how we approach generating them and regenerated all identicons. We do not have any indication that any personally identifiable information (PII) was leaked as part of this vulnerability.
Source and more information on this issue can be found here: We're regenerating all Gravatar identicons