My 5700X overclocked boosts up to 1.35V or slightly higher.
Understood the X3D V-cache is more susceptible to high voltage, but under 1.3V should be fine.
Using PBO2 Curve Optimizer to adjust the stock voltage curve negative is perfectly safe.
Ryzen R7 5700X | B550 Gaming X | 2x16GB G.Skill 3600 | Radeon RX 7900XT
Ryzen R7 5700G | B550 Gaming X | 2x8GB G.Skill 4000 | Radeon Vega 8 IGP
Ryzen R5 5600 | B550 Gaming Edge | 4x8GB G.Skill 3600 | Radeon RX 6800XT