It only appears occasionally. I have no alarms set, no timers, stopwatch etc. running.
Android phone. Searching got no joy.
Update: it was a scheduled message in signal. Didn’t want to send my bestie memes too late at night. It does use the actual alarm icon though, weirdly.
Thanks everyone for your help!
Go to android settings > apps > special app permissions (the last option) > alarms and reminders
The app causing the issue should be there, among others