Haswell Refresh is where things started to go wrong. 14nm stumbled such that refreshed +500MHz 22nm Haswell was a more compelling desktop product than delayed 14nm Broadwell. It was the largest single generation increase in clock speed and it wasn't even a generation

2011 2600K: 3.8GHz
2011 2700K: 3.9GHz +100MHz
2012 3770K: 3.9GHz
2013 4770K: 3.9GHz
2014 4790K: 4.4GHz +500MHz
2015 6700K: 4.2GHz -300MHz
2017 7700K: 4.5GHz +200MHz
2017 8700K: 4.7GHz +200MHz
2018 9900K: 5.0GHz +300MHz
2020 A900K: 5.3GHz +300MHz
2021 B900K: 5.3GHz
Given estimates of stacked cache Zen 3 I don't think Intel can give up even a few hundred megahertz on Alder Lake if they want to stay competitive on desktop.