I recently upgraded Firestorm from v6, noticed certain unicode characters in chat and hover text exhibit the bug, installed LL's viewer, saw the same issue.
I was told by Monty Linden in the last server meeting to file a bug report for the viewer to get a font pack update.
Here are a few out of many problem characters:
[2025/04/29 05:36:35] llOrd(textbox): llOrd('🗕',0) = 128469 (0x1f5d5)
[2025/04/29 05:36:46] llOrd(textbox): llOrd('🗙',0) = 128473 (0x1f5d9)
[2025/04/29 05:36:51] llOrd(textbox): llOrd('🞁',0) = 128897 (0x1f781)