passcode requirement for icloud use - divulging iphone passcode to apple

Hello,

As many people have, I got the announcement that I needed to enter my iPhone passcode to continue using iCloud.

I am reluctant to send my passcode to Apple as I wish to be the only one to know it. I have read with the advanced protection mode, the encryption keys are stored on my iPhone rather than on Apple servers. I have read that I am the only one who can unlock my phone. However, because I don't understand the security process, I feel uncomfortable entering my passcode to be sent to Apple.

Can someone explain how the one-way encryption keys are generated and sent and how Apple cannot unlock my iPhone even if I'm sending them my passcode for iCloud use?

I don't store data in the cloud (only on a mac) but I still would like to use FindMyPhone and Airtags which require me to enter the passcode.

Thanks in advance!