Issue about RPA in paper

[essentialsa]

acording to the figure1,step k ,level 2 the RPA take 𝒇𝑖(𝑘,2) as input and concate 𝒉𝑖(𝑘−1,2) to get the feature 𝒉𝑖(𝑘,2) of stepk level2,
but in the formula, it using the 𝒇𝑖(𝑘,l-1) , so the input should be 𝒇𝑖(𝑘,1).
It seems contradictory to each other, i can not understand it clearly.

[integralSF]

I also discovered this issue when I looked at the paper, also troubled me