Background information (includes intended features)

Pressing "Sneak" while in scaffolding will let the player climb down, and pressing "Sneak" while in other climbables will stop the player from climbing down. This occurs properly in both games (Bedrock Edition and Java Edition).

The glitch (the purpose of this ticket)

When sneaking on scaffolding while the player is inside of a non-scaffolding climbable block (ladder, vine, weeping vine, twisting vine, or cave vine), the player cannot move horizontally at all. Any input or knockback executed on the player will do nothing.

Video Example

https://youtu.be/ORHo1nm81sU