Minecarts with chests that are full stop on rails while minecarts with chests that are half full or less function normally. The more full they are, the slower they go. I checked and only found this bug affecting the Bedrock version in the bugs that are already reported. This is the Java version so it needs its own report. Please don't mark this as a duplicate of that issue since they are not the same versions.
This sounds very much intended.