Up to 1.5V is common with a properly set up, and especially stock, Ryzen 5000 processor. But
AMD has said it's not unexpected to see it hit even higher than that if it's a really 'chilly' CPU.
Totally agree, only undervolt Ryzen 5000 CPU's using Curve Optimizer. Many people do undervolt using VCore offsets but that generally ends up hurting performance... so it's a generally a bad idea. It's called 'clock compression', when it's reporting high clock speeds still but not actually achieving them in use. It happens when the CPU can't get the voltage it's requesting so it pulls back performance to maintain stability.