Meaning
An exclamation mark drawn in white or pale grey with a thin outline, the muted version of the red ❗. It signals a note or mild emphasis rather than an alarm.
It is handy for small reminders, side notes and tips in neat, minimal posts: “Bring your own cup this time❕” People who like aesthetic layouts prefer it where red would clash. On white backgrounds it can almost disappear, so check how it looks before using it in a banner.