Steps to Reproduce:

1. Build a rail track with a powered powered rail going straight into a block (see video).
2. Place the TNT Minecart on one end and modify it to set its explosion_power nbt tag to 0.0f.

   data modify entity @n[type=tnt_minecart] explosion_power set value 0.0f

3. Push the TNT Minecart into the side of the block using the track, causing it to explode.

Observed Result:

The powered rail the TNT Minecart was on breaks, and sometimes the block below it will break too. Due to the randomness of explosions, you may need to repeat this a few times to get this result.

Expected Result:

No blocks are broken as the explosion power is zero.