Since I joined the main Ubuntu Discourse site, in late 2024, I have observed the "flakiness" with the avatar rendering, in all contexts, as well as a sluggishness in response.
I don't understand enough to explain it, but with so many Categories, and Sub-Categories and Tags, in order to be as "specific" or "inclusive" as possible, the complexity associated with all those permutations, must ... in my mind ... impact the server's capacity to fulfill the demand, especially if it needs to deal with any sizable fraction of the 27K+ membership!
This last point underlines the fact that, when something gets too big, it becomes unwieldy, sometimes to the point of losing its effectiveness in delivering on the stated intent.