While there is certainly some truth to your statement, the subsidies being referred to in the article are on installed panels. Prices on panels were held high by subsidies, and their removal resulted in a market supply glut. This 10-15% raise is just the correction from the previous ~30% fall.

That had already occurred. This article was talking about a glut due to China dropping local installation subsidies. Demand dropped in China so all those panels were dumped on the international market.

The party being referred to was had by nonChinese developers, as they were getting panels cheaper than anticipated. That meant more profit for them.

The article says Chinese solar is 30% of the world production, not sure if that’s enough to jack prices.

30% referred to total installed capacity, not production.

It isn't so much that, as many producers were selling very low to get money coming in. These producers have now gone bust/ been bought up.

Now that those forced sellers have gone there isn't anyone willing to undercut everyone, so theres some support to prices.

... or drop the quality of the current products.

aka "The Walmart Playbook".