2018 Hyundai Elantra brakes problems

About month ago Sept the car would shut off when driving or stopping and find out it oil I had changed at the tire shop it was changed 2 n half months before that once oil changed running good low tire light ,oil light flash off and on at time well as of 10/12/2021 started do it my again so I check oil there no oil werid where oil go no leak on ground when I leave wherever I parked well went to Walmart get oil put oil in it and started driving not even more 35 miles bout sudden smoke coming from under engine then…

I have mid 26k miles I checked my brake fluid and pads they are both good. The brakes for the past 3 months roughly 15k miles (I drive 5k miles a month) have been spongy and soft. Unless I hit the brakes hard they barely work. Sometimes I have. To pump my brakes 2 or 3 times to have them feel normal. I'm going to take my car to the dealership and look over the ABS system and braking system since it seems very unsafe and I have a newborn. It seems like the car only does it at speeds above 25 or 30MPH