To anyone in this thread experiencing this issue, let me add a discovery I made yesterday after updating my MacOS to Sequoia 15.1 on a Mac Studio and also on a MacBook Air. The behavior is the same on both.
In the Desktop & Dock section of the Settings, you can turn off the option to tile windows when they are dragged to the screen edges, but in my experience there is no such thing as a "screen edge". Regardless whether your system has 1 or more displays, there is no "edge" on either the left or the right side, no matter if this option is on or off. Windows dragged to the side edges simply continue sliding until only a portion of the window remains visible, unless an additional display allows the window to move to that display entirely, and then the same thing applies when the window is dragged to the edge of that window. Likewise for "bottom" edges of screens.
In regard to any "top edge" my experience is that menu bars prevent windows from being dragged beyond the menu bar, unless you forcefully drag the window to go beyond the menu bar, in which case Mission Control is invoked to enable you to locate the window on an alternate desktop "space".
Now, in regard to the second option for making windows will the screen when dragged to the menu bar, my experience on both my Macs is the same. If you turn off the option and close the System Settings, you will find that it turns itself back on again when System Settings is re-opened. Consequently, the Mac is always expanding windows to fill the entire screen ... (to quote Donald Trump) "whether you like it or not."
Why Apple felt the need to add this peculiar feature is a mystery to me. The green dot in the upper left corner of any window already did this nicely enough.