I think the fact that this isn't "All of the money..." is a big sticking point for a lot of people. The article below is a little dated (Sep 2023) but some of the expenditures raise some eyebrows.
America has provided more than $70 billion in aid to Ukraine. The money has not just gone to the military, but also to help farmers, small businesses and first responders.
www.cbsnews.com
Things I don't personally think further the national security interests of the US:
1. "The U.S. government is subsidizing small businesses in Ukraine..."
2. "The U.S. government has also bought seeds and fertilizer for Ukrainian farmers."
3. "America is covering the salaries of Ukraine's first responders, all 57,000 of them."
4. "The U.S. funds divers who clear unexploded ammunition from the country's rivers to make them safe again for swimming and fishing."
Combine stuff like this with a historically corrupt government (also discussed in the article) and a myriad of domestic issues that could be solved by this money, and it's not hard to see where the growing national fatigue is coming from.