Major - P3 JsonWriter output was designed a long time ago and is currently incompatible in a few minor ways with current versions of the server and the shell, as well as with mongoimport.
In particular, the following needs to change:
Strict output mode:
BsonMaxKey: { $maxkey : 1 } => { $maxKey : 1 }
BsonMinKey: { $minkey : 1 } => { $minKey : 1 }
BsonTimestamp: { $timestamp : 64-bit-value } => { $timestamp : { t : 32-bit-value, i : 32-bit-value } }
BsonUndefined: undefined => { $undefined : true }
Shell output mode:
BsonMaxKey: { $maxkey : 1 } => MaxKey
BsonMinKey: { $minkey : 1 } => MinKey
BsonTimestamp: { $timestamp : 64-bit-value } => Timestamp(32-bit-value, 32-bit-value)