You are very correct. Obsolete weapons are been disposed and replenish with modern sophisticated weapons. But you shouldn't assume that it is only NATO that is rearming and gaining strength. Russian and it's partners are also doing the same. The reason for the stalemate in the war is because both parties are becoming stronger.
Yes, Ukraine is now recycling on its front almost all the remnants of Soviet military equipment, which is collected throughout Europe, and not only in Europe. This already outdated Soviet equipment is being replaced in Europe by newer models of NATO military equipment. In addition, equipment and ammunition whose service life and shelf life are expiring and NATO countries had to spend decent money on their disposal are successfully disposed of by Ukraine among Russian troops. Also, for NATO countries, Ukraine is a good testing ground for testing new types of weapons and equipment directly in combat conditions.
But Ukraine itself is also not lagging behind in this regard. Ukraine is the only country so far where a special type of military has been created - the force of unmanned systems. Moreover, Ukraine is now creating more drones than all European countries combined. When the United States suspended the transfer of military equipment and ammunition to Ukraine for eight months, the Ukrainian Armed Forces held back the increasing onslaught of the Russian invaders mainly through their drones.
Also, Ukraine is now actively developing and implementing robotic unmanned ground systems, since it is initially inferior to Russia in terms of the number of ground forces and the ability to mobilize its citizens. For the first time, war is becoming more technologically advanced, where the military controls their weapons at a safe distance, and in this regard, Ukraine has accumulated vast practical experience that no other country has. The Ukrainian Armed Forces is becoming one of the most powerful armies in Europe.