Bug only happens when minecart_improvements enabled.
Despite the rail (Rail, Powered_Rail, Activator_Rail) on the Slime_Block, the minecart jumps far into the air.

How to reproduce the bug ?

1. Place a Sticky_Piston
2. Than place a Slime_Block on it
3. Place a rail (Rail, Powered_Rail, Activator_Rail) on the Slime_Block
4. Activate the piston when you placed the minecart on the rail

Observed Results:
Observed Result.mp4
(The experimental_minecarts data pack is in this world enabled) Version 24w36a

Expected Results:
Expected Result.mp4
(The experimental_minecarts data pack is in this world disabled) Version 24w36a

Particularity: (The Detector Rail is excluded because it is intended that the minecart jumps off it (this is also the case in previous versions)