Renewables rose by far more than gas did. The overall market also grew. If you take coal and gas together and look at overall fossil based generation, it declined and continues to decline. The unspoken implication of nuclear proponents is that Germany started putting out more CO2 because they shut down nuclear. The reality is that there was a continuous decline in fossil fuel related emissions related to electricity production. So, who is being "dishonest" here?
Gas "sharply" rose to much less than the coal and nuclear reductions combined. Renewables are on track to grow to about an order of magnitude more than the nuclear capacity Germany ever had. New gas plants might still happen as that is part of their plan to decommission coal. Or at least it was until a few months ago. But it will probably never grow to close to the level of coal production Germany had 12 years ago when it started shutting down nuclear plants.
The decision to get rid of coal by 2030 is fairly recent. There are no international deadlines other than what was agreed at Cop 26, which thanks to China and India avoids any big explicit commitments. However, there is a lot of peer pressure especially in Europe to clean up the energy sector. Germany actually resisted that peer pressure quite long. E.g. the reason brown coal is still a thing in Germany is because until a few years ago, the CDU essentially blocked all attempts to kill that massively polluting industry to protect jobs. I think at the time of the Paris agreements they were thinking/hoping a 2050-2060 time frame. Germany even opened new coal plants as recent as two years ago. The ambition levels have of course increased dramatically in the last few years; mainly due to the success of renewables. Mostly this is driven by simple economics. People like cheap wind and solar energy. Nuclear they don't like for lots of reasons; including the bad economics.