Russia routinely runs low on missiles. That's why they aren't able to consistently saturate Ukraine with missile attacks. If they could, they would. Unfortunately for Russia, most of their production is cruise missiles and Ukraine's air defense (including aerial air defense platforms) has reached the point that most city centers are fairly protected from cruise missiles. The latest volley Russian sent, were overwhelmingly intercepted. Ballistic Missiles are still a challenge because only Patriot and SAMP/T can intercept ballistic missiles among Ukraine's air defense systems and Ukraine only has 9-10 of those systems combined, spread out across the country.
Russia's missile supply got so lo that they had to get them from North Korea to keep up their infrastructure attacks.
Russia's not going to run out of missiles. That was never the actual analysis. The argument was and still is that they would be limited their production, which means that they can't fire nearly as many as they want and certainly not as often as they want. They produce a couple hundred combined cruise and ballistic missiles per month and they use them. That's where we're at.
Russia has the same problem with their armor. They had a ton of it stockpiled, but they're burning through it. Eventually, they'll run out of what they can reasonably pull from storage and restore. In that case, they'll be limited to their new production, which amounts to approximately 200 MBTs and 500 BMPs per year. They are losing their armor at a much quicker pace than that, which means that eventually they will either have to limit operations, or resort to even more substantial meat waves, into the teeth of artillery and the evolving use of drones.
USA
now recognizes this. For the first time they sent anti-personnel landmines in a defense package, because they know that Ukraine can litter fields full of them and force Russian infantry to traverse through hell.