As with all things you need to understand your own threat model. For almost everyone storing your TOTP codes in your password manager, right next to the strong

As with all things you need to understand your own threat model. For almost everyone storing your TOTP codes in your password manager, right next to the strong randomly generated password, is perfectly fine and likely to be significantly more secure than the alternative options. If your threat model shows this to be a bad idea, you obviously need to do what is best for you. But for the typical person, this post can be easily ignored.