That's why 'fixed' overclocking of Zen 2 isn't really all that beneficial. And even if you do you often result in lower performance for light threaded apps, like games. PBO is the best way to get improved all-around performance.
Keep in mind that's a default value if you don't go through the process of determining your FIT (the voltage the processor's internal algorithm uses to keep it safe under maximum load/temperature conditions). You can go through a process of determining the true FIT, but it's rarely very much higher than 1.2V.