Look for California Online Public Schools’s own notice or letter: it should say what of yours was involved. Keep it.
The register’s list does not say what was exposed; the notice it links to (under Sources) usually does. If California Online Public Schools has a password of yours, change it now to be safe.
Expect scams that use your details: calls, texts or emails pretending to be California Online Public Schools, your bank or the police. Never give codes or passwords, never approve a sign-in you did not start, never move money.