I have a client in a deadlift rut. We've tried it all - light, heavy, high frequency, low frequency. And I've been there myself. I can say with absolute certainty, the thing that always works...stop deadlifting.
I know, "but I can't bro, my gains." If there's one thing that 2020 taught us is you can step away from the gym for awhile, sometimes a long while, and it all comes right back. The cool part is you usually come back stronger, and you always come back mentally refreshed.
With a blank slate, you step back up to the bar and through atrophy, have broken all of those old bad habits. You have a fresh start at feeling out your technique and getting into a better position.
It's worked for me about 4 times in my career, and I've seen it work both with training partners and clients.
So what can you do in the meantime? CARRIES!
Farmers carries. Trap bar carries. Fatbell carries. Yoke carries. Zercher carries. Med ball carries. Suitcase carries. Even a wheel barrow.
If you have a barbell, you're good to go, so no excuses.
Try this for 8 weeks. No deadlifts. All carries. Go as heavy or as light as you want. I promise you won't be disappointed after you come back to the deadlift bar.