What browser are you seeing this on? It looks like a styling bug in the CSS somewhere, potentially dealing with resolution somewhere to me. I use the change node like this on a daily base and it’s the first time seeing this. If you look closely the “delete field” button is also partially hidden.
Platform node red is installed on?
Version of node-res?
Platform you’re viewing this on?
What browser plus version of it?
Any special situations like are you using a browser on the device that runs node red through VNC?
What’s the screen resolution of the device running the browser?
As for a workaround, you’re dealing with two vertical scrollbars. One in the inner area that shows the rules (set/delete/... with editor for each), and an outer one for the node configuration field. To get so far down, put your mouse cursor to the top of the node config form (name field for example), then scroll down using your mouse wheel or equivalent. That moves the outer scrollbar instead.
Which firefox version would that be? Is likely relevant to reproduce it. Also screen resolution as it appears to fit the content to the limited space available and that’s why the double scroll bar happens. I might try to reproduce it tomorrow in a VM, if the resolution falls within common sizes