If we only look at the performance of these two CPUs, I5 12400 is definitely ahead of 3600x, I hope it will help your problem.

The following is a comparison.

Take cinebench R 15 as an example.

12400 single thread: 248 leads by about 2 1%.

Multithreading: 1780 is about 8% ahead.

3600x single thread: 205

Multithreading: 1650