When a DocumentCodec is configured in collection options, it is always used to encode the input document.

The input $document can be "array|object",

https://github.com/mongodb/mongo-php-library/blob/997923252e751768d871a0a6b1a79b8807d3c68d/src/Operation/InsertOne.php#L157-L161

while DocumentCodec::encode() only accepts "object": https://github.com/mongodb/mongo-php-library/blob/997923252e751768d871a0a6b1a79b8807d3c68d/src/Codec/DocumentCodec.php#L27

Reported by psalm:

PossiblyInvalidArgument
Argument 1 of MongoDB\Codec\DocumentCodec::encode expects object, but possibly different type array<array-key, mixed>|object provided