I'm not really sure what you mean here. You're talking about the main Mac menu bar, with "File", "Edit", "View", etc.?

If so, I'm not sure what to tell you. The tabs are a pretty large click target — much larger than, say, a link on a webpage. And various apps (e.g., Chrome, Firefox, Thunderbird) have tabs at the top like Zotero. Some are a little taller and/or have a few more pixels above, but others are shorter and don't have padding above. All standard macOS windows, including Zotero's, also have an invisible border of a few pixels around all edges where the cursor changes into a resizing cursor to let you resize the window, which also acts as a buffer. You can also just not keep the window at the very top of your screen (though if you're clicking outside of the window, you might temporarily focus whatever is behind the window).

We could consider making the tabs a little taller, but that would mainly be to make them slightly quicker to hit — I don't think we've had other reports of people missing them altogether.

OK, so you're talking about full-screen mode.

First, note that you can switch between apps instantaneously with Cmd-Tab, like Alt-Tab on Windows (but more powerful). I promise you you don't need to use full-screen mode to work efficiently on a Mac. This is critical enough to effective computer usage that we have a support article about it, even though it has nothing to do with Zotero specifically:

https://www.zotero.org/support/kb/switching_between_programs

As for full-screen mode, what you're describing isn't actually how it works. The Mac menu bar (with File/Edit/View) is at the top of the screen and never moves, ever. In full-screen mode, it just disappears. Different apps behave differently in full-screen mode when you move the cursor above the window to the top of the screen. Chrome and Safari just make the menu bar visible and unhide the red/yellow/green window controls in the top-left corner of the window. Zotero (and Firefox, on which it's based) slides down a title bar containing the window controls, and that does cover the top of the window with the tab bar. I agree that's not as nice, and it's possible we'll be able to do what Chrome and Safari do in a future version, but even Apple Photos does what we do, so it's not unprecedented. In any case, nothing appears unless you actually move your cursor above the top of the window. You certainly don't have to stop at the bottom half of the tab — if the title bar is sliding down, you're going above the top of the tabs.

Oh, I guess if you have a Mac without a notch, the menu bar and the title bar both slide down from the top, and your cursor would end up on top of the menu bar. But you still should have to move the cursor to the top of the screen to trigger that — if you think you're seeing something else, we'd want to see a link to a video. The only real difference from Chrome is that Chrome's tabs are taller. The space that looks like it's above the Chrome tabs is still a clickable part of the tabs.

In any case, I'd recommend just using Cmd-Tab to switch between apps and avoiding full-screen mode most of the time. People coming from Windows sometimes use full-screen mode because it's sort of like maximizing windows on Windows, but it's just not really the traditional Mac way to work, and once you're used to Cmd-Tab, multitasking that way is much faster.