My wife has long covid for 2 years with dozens of symptoms but not IBS.
She didn't get IBS per se; however, we have noticed a few changes with respect to her digestive system: she seems to have developed a recent sensitivity to wheat gluten and dairy/lactose. Both now make her gassy and uncomfortable.
The timing of it seems to be coincidental with COVID. Whereas we used to get pizza once or twice a month, it's basically been removed from our diet because it causes digestive issues.
So it's possible that some folks might not be having severe IBS, but a spectrum of digestive issues related to lingering effects that trigger inflammation with certain proteins/sugars?
I suspect the cycle is <something triggers GI inflammation> -> certain foods exacerbate the condition -> until inflammation or underlying cause of inflammation has resided, condition continues.
She has mostly returned to normal after losing many types of foods, but still can't eat beef or eggs in any quantity.