This feature was exclusively part of a joke version and is not currently planned for addition to regular Minecraft. It is documented here on the wiki due to being officially-released content by Mojang Studios, even if not present in a final version.
The Footprint was a joke item from Java Edition 20w14∞, found only in the missing dimension.
This item is semi-transparent with a grey colour scheme.
Obtaining
Dimension
Footprints were obtained only from a chest in the missing dimension. Only existing in 2020 April fools snapshot 20w14∞, it cannot exist in any non-April Fool's joke versions and April Fool's joke versions before or after 20w14∞. There is a maximum of 2 footprints that can be obtained legitimately in any given world.
Cheats/Creative Mode
Despite these footprints not being available in the creative inventory, it is still possible to acquire them via the command give <target> minecraft:footprint <amount> or duplicating them by holding down middle-click whilst in creative mode.
Usage
As of snapshot 20w14∞, this item cannot be placed or used in any way other than a trophy. This item can be inserted and/or rotated inside of an item frame, and it has a stack limit of 64.
Added the footprint item.
The Easter Egg dimension that the item spawns in.