Comment by TheDong

The reason copy+pasting is risky is it builds a habit where you're vulnerable to phishing sites.

Use the browser extension for your password manager, it auto-fills based on URL, so if you're on "kagii.com", it won't auto-fill and you'll notice something is off, but if you're on "kagi.com" it will.

Auto-filling vs copy+pasting is a security feature.