@ness_2510: I'm sorry to hear that you have encountered this issue on your Galaxy Z Flip4. If the issue persists, next time the alarm sounds, please head to Settings > Notifications > Recently sent, and check here to see if any apps are listed that correspond with the alarm (typically this would be the Clock app). If you're able to verify which app is responsible, head to Settings > Apps > Select the relevant app > Notifications, and explore your options from here.
I'm also having this happen on my Z-Fold 3. 6:30 every morning this week, I have had an alarm sound. No alarm set in the clock for this time, and I can't find it anywhere. I've tried clearing the clock cache, and still no joy.
I've just tried uninstalling the latest clock app update, so will see if this works tomorrow.