My iphone is deleting random photos how do I stop it from doing that?

If it is not in the Recently Deleted Album then either you have deleted them 30 days earlier or have never deleted any.

Please check the following

1. If you sign out of Apple ID sign backing with another Apple ID after you had turned on Messages in iCloud & iCloud Photos, your content is safely stored in iCloud and is available on all devices that use the same Apple ID.
2. If you have restored your iPhone with a backup that does not contain the Photos that you are looking for then please look for the correct backup on your PC/Mac --> Locate backups of your iPhone, iPad, and iPod touch - Apple ...
3. Do you have a correct backup (iTunes) --> Restore your iPhone, iPad, or iPod touch from a backup ...
4. If you have restored from iCloud backup, then note the following
   1. iCloud backup doesn’t include information that is synced and stored in iCloud, like Contacts, Calendars, Bookmarks, Mail, Notes, Voice Memos, shared photos, iCloud Photos*, Health data, call history, and files you store in iCloud Drive.
   2. *-If you had turned on iCloud Photos, your content is automatically stored in iCloud and is not backed up.
5. Probably you may have un-synced photos with Mac / PC, sync them again
   1. For PC: --> Sync photos in iTunes on PC with devices - Apple Support
   2. For Mac --> Sync photos between your Mac and iPhone or iPad - Apple ...
6. Have you ever imported your photos to Mac/PC and used "Delete After Import" --? Transfer photos and videos from your iPhone, iPad, or iPod ...
7. If not found anywhere, have you ever uploaded them to any Cloud Drives (iCloud Drive, Google Drive, OneDrive, DropBox, Flickr, box, AmazonDrive, Adobe Creative Cloud etc)

If you feel an unauthorized person/app is remotely using, controlling or monitoring your device, then that is possible only if you have done one or more of the following Don'ts...

1. Don't hand over an iPhone to kids or to a stranger without Enabling Guided Access
2. Don't share Apple IDs
3. Don't Jailbreak
4. Don't share sensitive information pertaining to your device
5. Don't give in to Phishing
6. Don't plug in your device in Airports and Public places through third-party cables and trust the device. Beware of Juice Jacking. (Especially in India)
7. Don't leave your iPhone unlocked and unattended in public places like offices, schools, malls, etc.

If one of the above is true then quickly change the Apple ID Password and Return iPhone settings to their defaults.

Internal storage or (if you're using iCloud Photos) iCloud storage almost full???

Check:

Internal storage:--> Settings>General>iPhone Storage

iCloud storage:--> Settings>[your name]>iCloud

Shouldn't be this case, there is no apparent reason why that could happen.

Giulio