After upgrade from Mongo 4.x to 8.x on old server, bsonSerialize() compatibility issue
If you upgrade from Mongo 4.x to 8.x and MongoDB stops working with: PHP Fatal error: Declaration of MongoDB\Model\BSONArray::bsonSerialize() must be compatible with MongoDB\BSON\Serializable::bsonSerialize(): stdClass|MongoDB\BSON\Document|MongoDB\BSON\PackedArray|array