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!
Just wanted to say scheduled signal message. Had this some weeks ago and it drove me crazy. Glad you found out by yourself!