Not sure what you're looking at. I am interested in the subject because I have a lot teachers public and private school in the family.
Most of what I see out there suggests to me there is essentially no correlation between changes in per-pupil spend and outcomes. If you go back to the 70s, you can't go much further back because you don't have a lot of comparable standardized test results before then, and stop pre-pandemic, what you see nationally anyway is educational outcomes are very flat even while (inflation adjusted) per-pupil spend jumped.
When you dig down to individual states, and/or mega districts (LA, etc) you mostly see that again outcomes stay pretty flat even in periods, even when major reforms (big increases in spend or cuts were made) even as you scroll forward a decade or on the outcome side to account for student experience.
From what I can see within a very wide-band of education spending, there is little impact on outcomes. Critics will find all sorts of exceptions but as I said in my previous post usually they end up being outliers to begin with. Sure you increased spending and scores did go up but it was in place where they were well below the curve to start with. Or people will say see see they spent even more money and scores dropped, but you look into and it was a place that was previously over performing, suggesting other factors probably are in play.