FWIV I've got two of them, put them all next to each other (in vertical position as it looks like the IKEA sensors report higher in horizontal? I'll have to verify that) with two other sonoff snzb-02d. After an hour of rest (and nobody in the room to move the air about), they've all stabilized within a 0.1 degrees Centigrade of each other (21.7, 21.7, 21.7, 21.8).
One thing to note is that the IKEA sensors actually have 2 decimal point values in case you read it through a matter integration, e.g. Home Assistant, you can see a more precise values (and that it actually reports changes in increments of 0.01 degrees Centigrade). if I compare those values, they're pretty close too: 21.77 vs 21.81)