Generally, a one-time password is an additional security measure that prevents someone from going to a website and simply using obtained credentials (eg from a leak) or brute-forcing them. An attacker needs the second factor.
If you store your 2FA secret alongside your password in a password manager, you still gain protection from these attacks. And it's very convenient. However, you also increase your attack surface: if they break into your password manager, your done.
If your threat model allows it (mine does), this is still very secure and also very convenient.
Generally, a one-time password is an additional security measure that prevents someone from going to a website and simply using obtained credentials (eg from a leak) or brute-forcing them. An attacker needs the second factor.
If you store your 2FA secret alongside your password in a password manager, you still gain protection from these attacks. And it's very convenient. However, you also increase your attack surface: if they break into your password manager, your done.
If your threat model allows it (mine does), this is still very secure and also very convenient.