I think the screenshots are self-explanatory:
Unicode emojis show up, as expected:
Searching here for “upside_down_face” won’t return this topic as a result.
I’m not sure it it classifies as a bug, and I don’t know either if strings wrapped with colons : should be excluded from the search (my feeling is they shouldn’t, even if the preview looks weird).
I initially posted this issue thinking it was a bug before understanding the behavior, but I prefer having it still written down here in case the issue is raised by someone else in the future.