New Safari windows do not open fully zoomed after update to Sequoia (macOS 15)

I always use Safari in its own space with the window fully zoomed (*not* full screen). For as long as I can remember, whenever I would launch Safari or open a new window, I'd get a window zoomed full screen as if the system remembered my last window size. In fact, even now, if I open a new Safari window, resize it to be 1/4 of the screen, close it, and then open a new window, that new window will be the same size as the one I just closed filling the same 1/4 of the screen, so it seems the system does keep track of recent window sizes. Immediately after updating to macOS 15, however, new Safari windows would no longer be fully zoomed. Instead, they appear to be fully vertically zoomed, but leave a small margin on either the left or the right of the window. Of course, I can hover over the green window control and use the new 'Fill & Arrange' feature to zoom to full screen, and I changed my system settings to fully zoom when I double-click the title bar since it's a lot faster than using the window controls. (Incidentally, I discovered there's no default system keyboard shortcut to zoom a window, which surprises me.) But it really bugs me that once I've zoomed a Safari window, if I close it and immediately open a new one, the system forgets I was just using a fully zoomed window and I have to take that one extra step to zoom it to full screen. I suppose this is more of a sanity check—am I nuts, or has anyone else noticed the same change in behavior? I've Googled around, and I see lots of complaints throughout the years about trouble using zoom controls, but I haven't seen anyone complain about this specific problem in Sequioa.