As the article mentions, "Military spending is doing that."
GDP is the term commonly applied to measure the economic "growth" of a country. It may be the single best tool for such, but far from perfect. During a war economy, GDP often increases but for reasons that break away from real and sustainable growth.
GDP = Consumption + Investment + Government Spending + Net Exports. Putin's Russia is heavy on consumption and government spending, but reduced exports and most importantly very little investment (except in building things that explode). Investment is the long term driver of economic growth.
More from the article:
...But spend big on the military and there’s less to spend on everything else.
“Longer term, you are destroying the economy,” believes Chris Weafer, founding partner of Eurasian consultancy firm Macro-Advisory. “There is no money going into future development.”
He says back in 2020 there was much discussion about the National Project programme, under which $400bn was to be spent on improving Russia’s infrastructure, transportation and communications. Instead, “almost all that money has been side-tracked to fund the military industrial-complex and support stability in the economy”.