Does air bubbles coming out during istinja and drying the private parts thereafter nullify wudu?

If the emission of bubbles is doubtful, then do not pay attention to it. If it is certain, then it nullifies ablution. Do not perform ablution until they cease. If anything is emitted during ablution, it must be repeated. As for drying the areas after istinja, there is no harm in it, and it does not affect the validity of ablution.