This solution doesn't make any sense. How does browser cache affect logins in apps like Windows Mail? I am able to log back in just fine on this PC.
Anyway, I discovered that all my credentials are gone from Credential Manager too https://answers.microsoft.com/en-us/windows/forum/windows\_10-security/all-of-my-web-passwords-are-gone-from-credentials/a8da7675-7924-4b1c-89e1-d82047cadb5b