Why does the password entry pops up on a delay at times?

The master password should either pop up right away, or not pop up at all until sensitive information will be accessed. It sometimes pops up on a delay, which is annoying, as I may already be typing something into the URL bar only to find that the second half of what I typed is now into the master password entry. During this time of delay, I am apparently still able to access web browser functionality. This creates inconsistent protection and makes me question what the master password is protecting. I thought I would only have to enter it before autofill, but entering it at startup implies it protects the entire functionality of the web browser, not just passwords. But, if it protects the entire functionality of the web browser, then why does it pop up after a delay, which is sometimes long enough for me to have already started to use the browser, meaning that, if my operating system account is shared but my browser is private, someone already could've made a social media post in my name in the time before they are required to enter the master password, if they are fast enough. Really think about your intention and please establish or make clear your philosophy with this confusing and annoying design choice. Is there a way to either stop the delay, or to make it only pop up when accessing autofill functionality, or to make the browser entirely inaccessible until the pop-up grabs focus?