Ukraine's mix-n-match tank destroyer performed well against Russian tanks for several reasons:

It has a powerful 100mm anti-tank gun that can penetrate the armor of most Russian tanks, such as the T-72, T-80, and T-90. It can also fire a guided missile through its tube for longer range and accuracy

It is cheap and simple to produce and maintain, using existing components from the MTLB and the MT-12 Rapira anti-tank gun. It can also carry up to 11 infantry or a cargo of up to 2,000 kilograms (4,400 lb), making it a versatile vehicle

It has a low-silhouette and can use its amphibious capability to cross rivers and lakes, making it harder to detect and target by Russian tanks and artillery. It can also use terrain features and camouflage to hide and surprise the enemy