Iphone 8 plus was stolen and was removed from my account after few months.

apple can't track their buyers products after sale it's against the law for them to do so in most countries in the world

your option are

If your iPhone, iPad, or iPod touch is lost or stolen - Apple Podpora

report the theft to the police in your country and to the carrier you use in many countries that will result in the IMEI being blocked by all carriers in the country

this

is a user helping other users with tech questions forum, you are not addressing

apple here just fellow users

if you wish to complain about apple not tracking your equipment then you should use their feedback channel

Feedback - iPhone - Apple

Protecting Apple ID and Password is the responsibility of every individual.

https://www.apple.com/in/legal/privacy/en-ww/

Erase your device. To prevent anyone else from accessing the data on your missing device, you can erase it remotely. When you erase your device, all of your information (including credit, debit, or prepaid cards for Apple Pay) is deleted from the device, and you won't be able to find it using Find My iPhone. After you erase a device, you can't track it. If you remove the device from your account after you erase it, Activation Lock will be turned off. This allows another person to turn on and use your device.

If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support

https://support.apple.com/en-in/HT201472