Spring football isn't flawed. How these leagues were funded and run is what's flawed. The USFL just completed it's season without incident and are ready for year two. That league is owned by Fox Sports with partial interest by NBC Sports. By their metrics the USFL was a success. They've already sold 65% of their adverting space for 2023.
The XFL, even with support from ESPN, was always a shakier proposition. They are already behind the USFL and they have a more expensive operational plan, playing in individual markets