I'm also wondering this. I got sick with a stomach bug a few months ago (not covid) and since then i have a tremendous amount of gas (from both ends). It starts about 5min after i start eating and gradually gets less as the hours go on until i eat again, although it picks up again when i haven't eaten anything in a while too. I can't figure it out. I haven't changed my diet at all from before and after i got stick to start it. I've tried cutting out dairy and also just going straight fruits and veggies with at least a week between each change but no luck. I also tried going on a probiotic diet for a while to try and cycle through and replenish good bacteria. I'm noticeably tired too which is probably because i'm not properly digesting the food to get the required energy from it.