IPhone 11 acting hacked or spyware

See -> If you think your Apple ID has been compromised

If you think your Apple ID has been compromised - Apple Support

To keep your Apple ID account secure, see the following Apple articles:

Manage and use your Apple ID

Manage and use your Apple ID – Apple Support (UK)

Recognize and avoid phishing messages, phony support calls, and other scams

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Phony "tech support" / "ransomware" popups and web pages

Phony "tech support" / "ransomware" popup… - Apple Community

Identify and filter junk mail in iCloud

Identify and filter junk mail in iCloud - Apple Support

Identify legitimate emails from the App Store or iTunes Store ->

Identify legitimate emails from the App Store or iTunes Store – Apple Support (UK)

Set up iCloud Keychain

Set up iCloud Keychain - Apple Support

Create a strong password for your Apple ID, It is best if your password consists of eight or more characters and include upper and lowercase letters, and at least one number. You can also add extra characters and punctuation marks to make your password even stronger. 

Never provide your password, passcode, security questions, verification codes, recovery key or any other account security details to anyone else. Apple will never ask you for this information.

See also the following Apple articles:

About the 'Trust This Computer' alert on your iPhone, iPad, or iPod touch

About the 'Trust This Computer' alert on your iPhone, iPad, or iPod touch - Apple Support

Authorize or deauthorize your computer for iTunes Store purchases

Authorize or deauthorize your computer for iTunes Store purchases - Apple Support 

Get a verification code and sign in with two-factor authentication

Get a verification code and sign in with two-factor authentication - Apple Support

Check your Apple ID device list to see where you're signed in

Check your Apple ID device list to see where you're signed in - Apple Support

If you have not jailbroken your iPhone and only downloaded apps from the App Store / iTunes Store then virus/malware is impossible.

Never visit questionable websites.

Soon after my iPhone 11 was acting strange and slower.

You may need to free up iPhone device storage see this Apple articles below:

If you need more space for an update on your iPhone, iPad, or iPod touch

If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

How to check the storage on your iPhone, iPad and iPod touch

How to check the storage on your iPhone, iPad and iPod touch – Apple Support (UK)

Clear Other storage on your iPhone or iPad

Clear Other storage on your iPhone or iPad - Apple Support

VPN can also be the cause of a slow internet connection, see https://blog.malwarebytes.com/101/2021/07/does-using-a-vpn-slow-down-your-internet/

See also ->The last update killed my battery!

The last update killed my battery! - Apple Community

See Lawrence Finch response in this thread about VPN.

About Jailbreaking see -> Unauthorized modification of iOS can cause security vulnerabilities, instability, shortened battery life, and other issues

Unauthorized modification of iOS can cause security vulnerabilities, instability, shortened battery life, and other issues – Apple Support (UK)

I used to leave my phone out and unattended around this person .

Then you should learn not to do it.

Never provide your password, passcode, security questions, verification codes, recovery key or any other account security details to anyone else.

Thanks for your feedback & you're welcome.