What should I do if a liquid that nullifies ablution exits during prayer, and its exit is repeated multiple times? And is ablution nullified upon sensing the exit of gas without smelling an odor or hearing a sound?

If the discharge is constant most of the time, making it impossible for you to pray with proper purification, or if its discharge is irregular, then it falls under the ruling of سلس ( سلس البول - urinary incontinence and similar continuous discharges). In this case, it is sufficient for you to perform ablution for each prayer after its time has begun, taking precautions (like wearing a pad), and whatever discharge occurs will not harm your purification. However, if the discharge is not constant and you are able to pray with proper purification, then it is considered a nullifier of ablution.

Regarding the sensation of gas exiting without sound or smell, it does not nullify ablution. One should be cautious of waswasa (whispers from Satan or obsessive thoughts) and disregard them.