What’s your actual point here? You seem to be trying to build up to something by asking me questions instead of RTFM.

You aren’t “sending” the key anywhere, you are downloading the report and decrypting it locally.

So you're saying that by logging into icloud.com and clicking on the "Find My" app, my web browser is downloading encrypted location reports from Apple's servers, and my web browser is decrypting them locally?

I’m saying that you should read the manual before asking such ignorant questions.

https://support.apple.com/guide/security/locating-missing-de...