why can someone else face open my ipone

Easily done when they know your Passcode. They can even add their Face to open your phone, since you can have more than 1 face to use Face ID. After changing your Passcode, you will also have to remove all Face ID data and set it up again.

adeyemo182 wrote:

The person know my passcode but not there when I set up my Face ID

Change your passcode, and do not share it.

As above: change your passcode and do NOT share it with people you do not trust. Also, re-establish your Face ID, being certain to do so with no one else present.

adeyemo182 wrote:

Please what can be the problem of my phone battery health decrease every single day because I don’t understand the problem please

Is this with the iPhone 11 and what is the current Battery Health?

Since the iPhone 11 was released in 2019, it is most likely that the battery should have been replaced at least once already. If you have already had your battery replaced:

• When was it done?
• Was it done by an Authorized Apple Service Provider?
• If the battery health is below 80%, it needs to be replaced.

Does this person know your passcode?

Were you in the room when this person opened your phone?

Was this person in the room when you first setup Face ID?

They say there are seven people in this world like each other.. Maybe one of them opened the face lock.