Daughter won’t poop on potty

Last month I was so proud of my daughter for finally pooping on the potty. But that excitement was short lived. She screamed and cried bloody murder because when her poop hit the water, she got splashed with some toilet water. I thought this would be short lived but flash forward to today. She wants nothing to do with the potty at all. Not pee, not poop, not anything. I’m still changing her diapers and she will be 4 next month. She’s currently in size 6 diapers and they are getting snug on her but they still fit. I refuse to buy her size 7. Help! How can I get her interested in the potty again?