Russell's admission came during an off-beat weekend in Austria, in which he was knocked out of Q2 of grand prix qualifying in 11th by Williams driver Alex Albon.
"Things just aren't really clicking at the moment my end," Russell admitted bluntly.
"At the start of the season I felt a lot more confident, and I was able to put the car on the limit. Now I'm struggling generally and have taken a step backwards compared to the rest of the field.
"So, I just need to understand that, take a reset tomorrow and into Silverstone and I'm sure it won't be long until I'm back to my normal level."
Russell didn't think Mercedes' radical development path, which led to a vastly different W14 from Monaco onwards, is one the reasons behind his form dip.
"No, I don't think so. I think it's just in your rhythm," he said. "The car's feeling pretty similar to what it did at the start of the year, some small changes. Nothing to do with the updates.
"Just sometimes things are just going your way and you've got that confidence. Sometimes you just lose a bit of confidence, and it has a bit of a knock-on effect. Especially when the car isn't optimal. So I know it'll come back."
After suffering from hydraulic issues in sprint qualifying, Russell advanced from 15th to eighth in the sprint race. The Briton said he felt much better in Saturday's colder conditions in Spielberg.
"The cooler conditions helped the balance of the car. Just from lap one in [sprint] qualifying, I felt confident, much more confident than yesterday," he added.
"The pace was good. I had a new soft tyre ready for Q3 today and I think we would have qualified in the top five or so. So, it's a shame."
