Iphone alarm turns off unwanted whenever i take it out of my pocket

See if "Back tap" is enabled for some functions:

Tap the back of iPhone to perform actions or shortcuts - Apple Support

I have it set to turn on the flashlight with a triple-tap, but sometimes the light comes on when I am removing it from my shirt pocket.

There could be several reasons why your alarms are not sounding or vibrating. Here are some troubleshooting steps you can try:

1. Make sure that the volume is turned up and not on silent or vibrate mode. You can check this by using the volume buttons on the side of your iPhone or by going to Settings > Sounds & Haptics and adjusting the volume slider.
2. Verify that you have selected a sound for your alarms. You can do this by going to the Clock app, selecting the Alarm tab, and tapping "Edit" in the top left corner of the screen. Then, tap on the alarm you want to check and make sure you have chosen a sound.
   1. Probably you have set the Alarm Sound to NONE. Watch the GIF below
   2. 
3. Check for Do Not Disturb or Bedtime Mode: If you have Do Not Disturb or Bedtime Mode enabled, your alarms might be silenced. Check the Control Center or Settings to ensure these features are disabled.
4. Sometimes, a simple restart can resolve temporary software glitches. Turn off your iPhone, wait for a few seconds, and then turn it back on.
   1. Restart the device. That's it.
   2. Still not solved --> Force restart iPhone - Apple Support
5. If the issue persists, you can try resetting all settings on your iPhone. This will not erase your data but will reset all personalized settings to their default values. Go to Settings > General > Transfer & Reset > Reset > Reset All Settings and confirm the action. Note that you will need to reconfigure your settings afterward. All settings—including network settings, the keyboard dictionary, the Home screen layout, location settings, privacy settings, and Apple Pay cards—are removed or reset to their defaults. No data or media are deleted.
   1. Reset All Settings: Return iPhone settings to their defaults - Apple Support:- Return iPhone settings to their defaults
   2. You can return settings to their defaults without erasing your content.
   3. If you want to save your settings, back up your iPhone before returning them to their defaults. For example, if you’re trying to solve a problem but returning settings to their defaults doesn’t help, you might want to restore your previous settings from a backup.
6. Make sure you have the latest updates installed.
   1. Update Over-the-Air (OTA) —> Update your iPhone or iPad - Apple Support (IN)
   2. Update using iTunes/Finder —> Update your iPhone, iPad, or iPod touch - Apple Support (IN)

If none of the above steps resolve the issue, it is recommended to reach out to Apple Support or visit an authorized service center for further assistance. They can provide specific guidance based on your device model and iOS version.

Alarm issues are not always the fault of the iOS update!  Many things can cause phone problems.  If you tell people you think it's an iOS update, it might make it harder to fix or find a solution for the real issue.

Remember, the right question often leads to the solution!

Was/Is your device Jailbroken? If that's the situation, please be informed that attributing the issues to iOS updates may not be accurate.

iOS updates aim to enhance user experience, boost security, and fix bugs rather than disrupt core features. The majority of the issues after updates might stem from underlying, unmentioned factors. Updates won't typically alter personal data but may refine settings or features. Backup before major updates for safety. Review Apple's update details and backup advice for a smooth process.

Kindly consider checking your settings and addressing any device issues before attributing the issue to external factors. This could be a pure coincidence that the iOS update affected the iPhone functions.

Before initiating a standard iOS update, it's advisable to create a backup. Have you completed this step? If yes, proceed with the restoration from the backup.

See what each update does: OS — iOS 26, About iOS 18 Updates, About iOS 17 Updates, About iOS 16 Updates, About iOS 15 Updates, About iOS 14 Updates, About iOS 13 Updates, About iOS 12 Updates, and so on...

I conducted a thorough search of this forum using the term 'Alarm after iOS Update' and uncovered numerous posts detailing similar issues across various iOS updates. This suggests that iOS updates may not consistently be the root cause. Below are a handful of examples extracted from the search results:

• Re: Alarm Clock sounds quietly for about 2 seconds and persistent sleep schedule issue after iOS 18.3.1 update...
• Re: Alarm sound missing after iPhone iOS 17 update
• After updating to iOS 16.2 Alarm volume became lower
• Why is my alarm not going off after I updated 17.0.03
• Alarm issues after taking iOS 14.5.1 update
• Alarm bug after 16.3.1 IOS Update
• alarm not working after iOS update to 11

The above issues span many models, and iOS updates suggest the issues reported by many are device-specific and erroneously attributed to iOS updates.

When you attribute every glitch or slowdown, or feature availability on your device to an iOS update, you risk overlooking other potential causes that may be specific to your hardware or settings. Updates often become the “easy scapegoat,” but not all issues originate from the operating system itself. 

Many people think the iPhone alarm might not go off at times, but it's usually due to a simple setting. Let's check a few things:

Is the alarm set for "Tomorrow" only? If you intended for it to repeat, make sure it's set for the days you need.

Is the alarm set for specific weekdays? Double-check that it's not accidentally set to a different day or multiple days.

Is the sound turned off? The alarm won't make any noise if the sound is muted or set to "None."

By checking these things, you can ensure your iPhone alarm wakes you up when you need it to.

Note:

Do Not Disturb, the Ring/Silent switch and Silent mode don't affect the alarm sound. If you use the Ring/Silent switch or Action button to turn on Silent mode or turn on Do Not Disturb, the alarm still sounds.

Warning:

Manually adjusting the time on your iPhone in Settings to change app behaviour, such as game timers, isn’t recommended and can affect alarms.

I am having the exact same issue since IOS update.

my alarm sounds and when I try and remove my phone from my pocket the alarm goes off which is annoying as I use my alarms for medication reminders and prefer to snooze the alarm until I know I have take them.

I’m here with the same issue, but no solution was provided in the multiple responses to your initial post. It’s been a bit since you posted, so I’m curious if you found a solution on your own. Thanks!