FPSreview has a nice review up. TLDR: no real big difference overall, ddr4 the wiser option for your wallet.
https://www.thefpsreview.com/2021/12/13/intel-core-i5-12600k-alder-lake-ddr4-vs-ddr5-performance/9/
https://www.thefpsreview.com/2021/12/13/intel-core-i5-12600k-alder-lake-ddr4-vs-ddr5-performance/9/