As of just a few hours earlier, the profile image icons for all of the 27 main sites I am a member of, and the network icon (i.e., showing in the upper right corner of my sites list), was
I've always had this same icon on every site since I joined each one. However, I just saw that my icon changed for this site, as well as for the Stack Overflow main site (but not its meta one), to this one instead
Note I have not done anything unusual recently, especially related to making any profile page changes. Also, I haven't bothered checking any of the other child meta sites I'm a member of to determine if any of their icons have changed, but I assume they have not.
FWIW, I'm using Microsoft Edge, version 113.0.1774.35, on Windows 10. Also, I'm using just a plain version of Edge, i.e., I haven't made any setting changes, there are no installed browser extensions, I don't have any user scripts, etc.
I did a site search to find Today my global User Icon changed. Why?, which was closed as a duplicate of Why is my profile image different? (from almost 7 years ago), but with this apparently being a somewhat different issue. Also, in the "Related" section, there's the quite similar Gravatar spontaneously changed this morning - only on Stack Overflow, but that's from almost 11 years ago, and the answers there don't apply to my situation. Finally, as starball's comment indicates, two other related questions are Identicon changed for no apparent reason and Unexpectedly changing identicon, plus this same problem has also just been reported on Stack Overflow Meta at What happened to my profile picture?.
The Stack Overflow Meta post & its comments, as well as a few comments below, indicate this issue is happening to at least several other members. Does anybody know what might be going on, as well as how to best resolve this?

