That is not a plane if you look close. That is thieving. The board layout had no copper there, but this can make the plating process more difficult to get consistent across the board. Usually this is added by the fab house to help them manufacture the board.

VSCode is open (MIT) but it is packaged by MS to include some tracking/telemetry and they are distributed under a non-free license.

You can use VSCodium for a telemetry free and MIT licensed binary or you are free to build the source where the default config is no telemetry and MIT license.