According to https://www.cfr.org/article/how-much-us-aid-going-ukraine, "It’s important to note that of the $175 billion total, only $106 billion directly aids the government of Ukraine. Most of the remainder is funding various U.S. activities associated with the war in Ukraine, and a small portion supports other affected countries in the region." Of that $106, about $70 billion is weapons, $33 is budget support. So it makes sense that lawmakers would claim that "We sent Ukraine $175 billion!" and Zelenskyy would directly see less than $175.

The the line from Zelenskyy is an attempt to clarify to the world that $X billion in a bill somewhere doesn't equate to $X billion on the ground in Ukraine directly; he's not saying there was some kind of corruption involved and that the money mysteriously disappeared.