How to stop the contact Photo on iPhone that Changes without my permission?

This makes me so mad also. I text with a lot of teenagers for my job (I'm a private tutor) and I don't want pictures of teenagers in my contacts or of their parents. It used to be an option to accept a person's contact photo but now they're just appearing and I have to spend time making a custom poster of their initials on gray instead of the photo they've chosen. I'm mad enough to leave Apple.

Smartphones lack both the inherent intelligence and the capability for malicious intent. Therefore, it becomes imperative for us to pay close attention to our device settings and the manner in which we synchronize our smartphones with Mac/PC/iCloud. Additionally, we must exercise caution when sharing sensitive and valuable information with friends and family members.

Be careful when sharing the device's sensitive and valuable information with friends and family members.

Thumb Rules:

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.