A cushion is a placeable entity that can be sat on. Cushions can be placed on any surface within any block in the game, excluding fluids and a few invisible blocks, and break shortly after their supporting block is removed. Cushions always drop themselves when broken.
Cushions are entities, meaning that they cannot be mined like a typical block. Instead, cushions immediately break when attacked, including with projectiles, or by non-player entities, even if the damage received is 0. A cushion also breaks when a piston attempts to move it.
Like paintings and item frames, cushions also break if they don't have a support block. The existence of a support block is checked every 100 game ticks (5 seconds), starting when the entity is loaded.
Cushions can be found naturally in abandoned camps. They normally spawn within 1–2 blocks of a campfire, assuming the camp generates with one. The color depends on the template, all 16 can be generated. See Abandoned Camp § Components for more details.
Cushions can be placed on any flat surface, and align horizontally to the grid unless teleported, but vertically sit on top of the supporting surface. They break if their supporting surface is removed or if they are pushed by a piston. Since they are entities with a finite amount of health, they also break after a few seconds if placed in lava.
They can be sat on by pressing use on them. Players cannot be affected by portals or forms of movement (e.g. knockback, geysers and pistons) while sitting on a cushion, but will become affectable again once they dismount.
Cushions cannot move, do not have collision, and can overlap with other objects, except for other cushions and custom blocks in Bedrock Edition. This means they can rest properly on top of any surface which is less than one block in height, including snow layers, wildflowers, enchanting tables, slabs, and stairs. Cushions placed on the lower step of stairs are partly obscured by the upper step of the stairs.
Unlike wool-based blocks, cushions do not dampen vibrations from sculk sensors or sculk shriekers. Placing, breaking, walking, sprinting, jumping, sitting on, and getting off a cushion produce detectable vibrations.
Since the cushion is an entity, it means that it can be placed very freely if we don't add any like additional placement rules. And I remember discussing this with the team, and we decided that we indeed should embrace this creative chaos and let the players place the cushions in any way they want to. And it was a bit of a chaotic decision, but I'm feeling very happy about it,