Floor Warp is a glitch that causes the player to be clipped down into the floor after entering a map transition.
[section=How-to] The glitch depends on how maps are made so for every instance of Floor Warp, there is a different way of triggering it. Although all involves touching a wall when entering a map transition trigger.
[section=Explanation] Floor Warp happens when the player is stuck at any point during the map transition. Exactly how the game handles this is still unknown due to being obscured by tons of code.
This can be the case if the transition area between 2 maps is badly made with walls or props not aligning to each other correctly. This can be seen in the Ninja Clip
[small]Base of the metal beam in both maps, if the player presses themselves against the beam on the previous map, they'll be stuck on the current one.[/small]
Sometimes when the player is between 2 sloped surfaces which are not world brushes (i.e. func_brush, func_detail, ...), they can get stuck due to the weird collision caused by them running into the surfaces. This can be seen in the first half of the Questionable Ethics skip
[small]The 2 sloped surfaces the player walk between and touch while entering the map transition.[/small]
Once the game notices you're stuck while transitioning maps, you will be instantly pulled down into the floor similar to Save/Load Buffering while in stuck in a brush.
[section=Notable uses] bm_c2a4f - Questionable Ethics skip - skips the majority of the chapter Questionable Ethics. bm_c3a1b - Ninja clip - skips the entirety of the map bm_c3a1b of Lambda Core.