How to the get the reference of the second window opened by a window in JavaScript?

I am trying to make an application which based on the current time, redirects you to certain links, in my case these are google meet links(different links at different days and times).Now all my links are in lookup format, so they first ask you to sign in, and then you get access to the meeting itself. So this is the problem I am getting :- I have a function which executes every second(setTimeout), and in each iteration, it checks the current time, and redirects you to the meeting. For that I am using window.open(meeting url(lookup format), _blank), to open this link in a new tab(Using Firefox), and then what I want to do is that if the user accidentally closes this tab, or it gets closed for some reason, this function will reopen that tab almost instantly. So to check if that new tab is closed or not, I saved the window reference in a variable called winRef, which allows me to check its state using window.closed property, but the problem is that that winRef actually gets assigned to the reference where the URL is of that “sign in with” window, whereas what I want to do is get the reference of the actual meet window, which comes after I sign in with my mail id.

And yeah, I really need that sign in feature