Your image contains Snap!_SRC Data Payload Embedded
So there are different files served for other users.
It is probably caused by the serwis worker and offline storage.
Edit:
Different computer - image is served as https://forum.snap.berkeley.edu/uploads/default/original/3X/6/6/666a9f1e0ee66a1115051021e40784a2b4818ec9.png
Discourse lives its own internal life...
