Data leak, data breach & iOS notifications.

How accurate are these alerts, can they be false positive alerts, caused by a buggy IOS update etc?

After changing nearly every password for every site I use, using keychain and/or two-factor security I still get the alerts showing data breach?

How safe is Apple Keychain for storing passwords?

How can Apple be secure, if it can tell me my password isn’t safe, is the program that’s reading my passwords safe?

Can a leak easily come from within Apple, if my data is readable by Apple themselves?

I believed my passwords are stored & encrypted in keychain to everyone & any program except to myself?

If the Apple ID is leaked there’s always a higher possibility of being hacked, now if after changing my passwords, using keychain, still getting data leak alerts am I right to assume it’s very likely my username/Apple ID is the issue?

And if my Apple ID is the issue, which carries my history, settings, Apps, purchases etc can the ID name be edited or am I forced to create a new one instead and lose everything else?