No, this is actually solar's output increasing.

Natural gas's share of electricity generation has been falling for five years straight:

https://ember-energy.org/latest-insights/gas-share-in-global...

That's a link to a global chart. The OP is talking about the US. It's not surprising that countries that have to import natural gas are moving away from it and countries with plentiful local suppliew are doubling down on it.