In 2020, with a much larger field, he got 26% or 27%.
This time, he got the plurality. But if you view the Democratic party as "Bernie vs. not-Bernie", he's getting much less support this time.
In Iowa, Warren + Bernie 2020 = about the same as Bernie 2016
But if you think of Warren as her own thing, very different from Bernie, then it's worse news for Bernie.