Right Side Back Pain w/ Deadlift

Since last week I got some sort of back pain whenever I do deadlifts. First it was only when I lowered the bar. Yesterday I focused more on the pain and realized that it appeared more on the right side of the lumbar spine. I also noticed that pain decreased when I stood erect but bent my torso some degrees to the left side.

Then it came to my mind that it could be my right hip whats causing problems. So I sat down and did the 90/90 stretch and my right side felt really STIFF. But after I got up I noticed that the pain was immediately gone. Could immobility of the hips be a problem?

Any ideas of some mobility work? Shall I deload deadlifting too? Or avoiding it at all? I’m not sure what to do know, I just started Waterbury’s 10/10 transformation, and there are many deadlifts included there.