Dragon Ball Super is in a strange place on the timeline of the overall franchise. So far, its events cover everything between the defeat of Kid Buu and the 28th World Martial Arts Tournament. This should have meant the series would eventually line up with the canon ending of Dragon Ball Z and, by extension, its sequel series Dragon Ball GT. However, Super has made several delineations from this part of the franchise's canon, which leaves its future uncertain. At the rate Super is changing events from the original series, it could overwrite the ending of Z and render GT non-canon.
Source：https://www.cbr.com/dragon-ball-super-undoes-gt-canon/
