Steps to reproduce

1. Set up a minecart next to a fire block.
2. Make sure there are no other blocks where the player could exit the minecart within 1 block in each direction.
3. At the same X, Z as the fire block, make sure there is a solid block to stand on at Y -1 or Y 0, and 2 blocks of air above the solid block.
4. Enter the minecart.
5. Exit the minecart.

Expected result

You are standing on the block that the minecart rests on.

Observed result

You get teleported to the same X, Z as the fire block and Y 0 or Y 1.

When leaving the minecart in the orientation shown below, if y=0 and y=1 are air blocks then the player gets teleported to the coordinates of the fire beside, but at y=0.

A video of this happening can be found here https://www.reddit.com/r/Minecraft/comments/wxjof4/this_bug_lets_you_instantly_teleport_to_y0/

Edit: This can also teleport you to y=1 if y=2 is air, but cannot teleport to y=2 and above. This teleports the player regardless to if there is ground beneath the player, meaning if there is no ground you tp to y=0 and fall.