Minecraft wiki entry for Barrier, associated text: The symbol used is not compliant with ISO 3864-1, as the diagonal line is mirrored.[5]
Invisible bedrock, a technical block in Bedrock Edition, shares many features with the barrier block.
The barrier's vanilla block model defines only what texture to use for block breaking particles, and doesn't have a parent model or anything that would give the block a physical shape.
Barriers are hardcoded to not render any block model.[6]