I don’t have an issue having a master password for one password manager stored inside another; I DO think having it in a web browser's built-in password manager is a bad idea, particularly because most browser password managers don’t require authentication to use (unless you’re logging into the browser for the first time).
If someone gets access to my unlocked machine and can get into my web browser, they could potentially get into my other password manager to retrieve important information. That’s a very bad thing.
Sometimes you’re required to enter a password to retrieve/view saved passwords in a web browser, sometimes you aren’t — but it is very rare that the built-in password manager requires authentication for auto-fill. As a general rule, I don’t use Chrome's built-in password manager for anything sensitive because it didn’t require prior authentication to view stored passwords (it may have changed now, but I’m not sure), and the same is true for autofill of my 1Password master password and security key on ANY platform. I don’t want someone to be able to autofill and get access to all my data.
If someone gets access to my unlocked machine and can get into my web browser, they could potentially get into my other password manager to retrieve important information. That’s a very bad thing.
Sometimes you’re required to enter a password to retrieve/view saved passwords in a web browser, sometimes you aren’t — but it is very rare that the built-in password manager requires authentication for auto-fill. As a general rule, I don’t use Chrome's built-in password manager for anything sensitive because it didn’t require prior authentication to view stored passwords (it may have changed now, but I’m not sure), and the same is true for autofill of my 1Password master password and security key on ANY platform. I don’t want someone to be able to autofill and get access to all my data.