TL;DR is three major factors:
1. The agencies that are doing the estimates are _very_ bad at exponential development curves (cough cough IEA estimating solar [2])
2. Unfortunately much of the developing world's economy is not growing as fast as we previously thought it would (similar thing happening with birthrates)
3. Many costs are absolute and _not_ marginal, which is just wrong IMO. We are going to need the energy either way, we should be talking about the "green premium" (as far as it exists), not how much it'll cost to generate XX TWH of energy
[1]: https://www.economist.com/interactive/briefing/2024/11/14/th...
[2]: https://www.economist.com/interactive/briefing/2024/11/14/th...