Sugar free soda can have artificial sweeteners that can make ibs way worse. As someone with chronic gut issues, I avoid sugar free soda big time. Your triggers may be different, but I’d suggest going without it for a week or two and seeing how you feel.

Instead I drink carbonated water (and a lot of it). I get the plain water, squeeze a lime in it and add a splash of pure (unsweetened) cranberry juice. It’s better than soda, imo.

There was a subreddit called /r/beansinthings - not sure if this is related. Same kind of posts tbh.