Why does my 3x5 5x5 deadlift routine with a 45 kg bar stall at 120 kg despite progressive overload?

I feel like I've hit a brick wall with my deadlifts. For the past 8 weeks I've been running a classic 3x5 5x5 split, adding 2.5 kg every session on the 45 kg Olympic bar. My numbers were creeping up nicely—115 kg, then 117.5 kg—but now I'm stuck at 120 kg for three straight workouts.

A few things that might be relevant:

• I'm using a standard 20 kg plate set, no specialty bars.
• My grip is mixed (hook on the first set, double overhand after 2 reps).
• Sleep is solid (7‑8 h), carbs are around 2 g/kg, protein ~1.8 g/kg.
• I’ve been doing 3‑4 min rest between sets, but the bar feels heavier each rep.

What’s driving this? Is it a neurological ceiling, a hidden mobility issue, or just the dreaded “gym bro” myth that you need to switch to a deficit deadlift? I’ve tried adding a paused rep at the knee and a few deficit pulls, but the plate still won’t budge.

Maybe I’m overthinking the programming and need a deload, or perhaps my hamstrings are the weak link—anyone else seen this exact plateau? I could really use some validation that I’m not just being a wimp about a 2.5 kg jump.

Thanks for the input, and feel free to call me out if I’m missing something obvious.