Not earth-shattering or even particularly troublesome, but a curiosity:
Occasionally, when I think I’m opening a new tab in Chrome, after some period of time I discover that I have instead opened a whole new Chrome window. I never notice it when it just happened so that I could re-construct what I did, so it’s still a mystery to me how this happens. (I only mention Windows 10 because I don’t remember this happening before I had that OS, which has only been maybe 4 months.)
I’ve tried to look this up but I don’t seem to get anything that addresses this particular question. I think I know how to change the setting to always get a new window instead of a new tab, but I can’t see how I’m accidentally doing it once in a while.
I suspect you are accidentally dragging a tab out of the title bar. Chrome considers this “tearing out the tab” and will make a new window with just that one tab.
There’s no way to turn this feature off in Chrome, so my only advice is to make sure your mouse cursor stays in the upper part of the tab. If it goes below the tab bar at all, it will tear out that tab.
Well, that and that there are two other ways to make a new tab besides clicking the new tab button:
Ctrl-T (not Ctrl-N, which is a new window)
Type a new URL in the address bar, then middle click on the arrow button.
There are possibly other ways to accidentally create a new window, but tearing off tabs from the tab bar is the most common, I believe.