The bug

In previous versions, dismounting from a minecart after travelling would place the player on a solid block on either side in preference to stair blocks. (The stair blocks here are placed so that they do not have a solid top face.)

In 1.16.2, dismounting from a minecart after travelling always places the player on the right in relation to the direction of travel. All stair blocks are counted as full blocks regardless of orientation. This breaks particular minecart systems that dismount on left, and bidirectional minecart tracks.

If the player has not been travelling and the minecart has just been placed, dismounting always places the player on the block that is north of the minecart. This is also incorrect.

The attached image 2020-08-21_22.15.39.png shows the orientation of stairs, and places where the player can dismount from a minecart (manually at unpowered rails, and automatically at activator rails).

This may be related to the change to the respawning mechanic introduced in 20w30a.

How to reproduce

1. Construct rails with stairs, unpowered powered rails and activator rails as shown in the illustrations
2. Travel from one end to another
3. At the activator rails, the player always dismounts on the right in relation to the direction of travel
4. Dismount manually at the unpowered powered rails after travelling -> The player always dismounts on the right
5. Place a minecart on unpowered rails, enter the minecart and then exit -> The player is always placed on the block adjacent to the rails towards the north