The Gintama manga's ending was delay multiple times as the series was originally announced to end in September 2018. Turns out that the only thing that was ending its run on Weekly Shonen Jump as the series was moved to Jump Giga in December 2018. The reason for the switch of magazines is that Sorachi needed a bigger page count to reach the ending, and a weekly magazine's page count was not enough.
The Gintama manga's final arc, the Silver Soul Arc started back in July 2016.
[Source: Anime News Network]