Breaking a minecart containing a block drops separate items for the minecart and the block (i.e. breaking a chest minecart drops a minecart and a chest, not a single minecart with chest item).
While this behavior is certainly not a bug (it has always worked like this), but it is inconsistent with how chest boats work (
MC-249379 - working as intended).
How to reproduce
1. Place a minecart with chest.
2. Break it.
A minecart with chest item is dropped, given the resolution of
A minecart and a chest are dropped separately.