SZA’s voice isnt traditionally good even on wax, so not surprised it sounds funny live.
That said, she doesn’t sound
too off from her records. she sounds like she had a combination of issues going on. She needs vocal coaching for live performances, she needs to do some cardiovascular conditioning and practice singing while moving (I remember Beyonce saying her dad had them running 3-5 miles a days while singing so they could hold notes thru movement), and lastly she kinda seems shook, Coachella is big as fukk, might be the biggest (and most important) crowd she’s played thus far, nerves may have gotten to her.