The ruler is on in options. When I turn on View → ruler the white canvas movies down but no ruler shows up.
You’ll see a bit of black below the toolbar and above the canvas (white).
Apparently you’re under a dark theme. Dark themes even now cause problem. Does it also occurs under a light theme? Since this kind of issue is strongly related to system, what is your OS? And LO version? Dark theme handling has been improved in 24.x.
Switching to light mode fixed it. Thanks!