You could try address bar search to find and switch to the tab you're looking for. There's a link to that on the "All Tabs" drop-down list in any window where the tabs are overflowing. This article illustrates what I'm talking about: Search open tabs in Firefox.

As for the order of the list on the Window menu on Mac, as a Windows user, I have no experience with that.

There is no arrow like that in the address or tabs bar. Oh, there is one in the address bar, but all that shows are a random list of previously closed tabs, not any currently open. Is there an order to the ones in the list of open windows on your computer?

You can always do this:

To search open tabs from the address bar, type a % character first, then type any part of the title or URL of the tab you want to find. The address bar drop-down should show matches with the "Switch to Tab" action indicated.

StevenCee said

There is no arrow like that in the address or tabs bar.

The "List all tabs" icon appears when the number of tabs exceeds the capacity of the tab bar (it gets scroll buttons on each end). Maybe you don't have enough tabs open? You could try this to show the button all the time:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

(2) In the search box above the list, type or paste tabman and pause while the list is filtered

(3) Double-click the browser.tabs.tabmanager.enabled preference to switch the value from false to true

I'm not sure whether that is supposed to take effect immediately, or only after a restart, it's a brand new preference in Firefox 73.

Oh, there is one in the address bar, but all that shows are a random list of previously closed tabs, not any currently open. Is there an order to the ones in the list of open windows on your computer?

The Show History icon in the address bar isn't related to open tabs, that drop-down shows your most visited sites.