Is it necessary to perform ablution if only bubbles emerge after using the restroom and sitting down?

If flatulence is certain to have occurred, then ablution is nullified and must be repeated, unless it reaches the extent of سلس (incontinence). If it reaches this extent, then one performs ablution after the entry of the prayer time and prays the obligatory prayer and as many supererogatory prayers as one wishes until the prayer time expires. However, if it is merely a whisper (waswasa), then the original state of purity remains, and it is not nullified except by certainty.