Hi, this issue #4649 is still happening in 4.2.4 with ID fields.

In QueryMapper#getMappedValue method, applyFiledTargetTypeHitToValue() returns the Pattern object correctly after the fix, but later ends calling QueryMapper#convertId() method, which ends calling getConversionService().canConvert() in MongoConverter.convertId() method. This is returning true, so Pattern is converted to String anyway.