Apple ID Compromised with Passwords and Phone Number Changed

First, attempt to use Account Recovery to gain access to the account, as you do not need access to the Trusted Phone number.

How to use account recovery when you can’t reset your Apple Account password - Apple Support

If you are still unable to gain access, then to remove the account from your devices, you will need to follow the steps here to get rid of the Activation Lock.

https://al-support.apple.com/#/additional-support

Thank you dearly. I have successfully recovered my Apple ID, though I still can’t be certain how it was possible that my Apple id’ phone number was even changed without my notice. Either ways, thank you

Were you using two factor authentication? If you were instead using Apple older security method of Security Questions, those were prone to social engineering hacking (in my opinion particularly how Apple had them designed).

Security and your Apple ID - Security and your Apple Account - Apple Support

Two-factor authentication for Apple ID - Two-factor authentication for Apple Account - Apple Support - "Two-factor authentication is an extra layer of security for your Apple ID designed to ensure that you're the only person who can access your account, even if someone knows your password." Uses a "trusted" device to receive a passcode to verify adding a device. Article also has a FAQ section and general information on how to set up and edit information.