If you check ?lfcShrink in current release it says,
For ‘type="normal"’, shrinkage cannot be applied to coefficients in a model with interaction terms.
So for >= v1.18 with apeglm or ashr shrinkage estimators, you can perform this. We haven't written up a full explanation of these in the vignette, it has a section that I'm looking to expand, but haven't had the time yet. Here is some demo code though for an interaction term:
dds <- makeExampleDESeqDataSet() dds$x <- factor(rep(1:2,6)) design(dds) <- ~x + condition + x:condition dds <- DESeq(dds, quiet=TRUE) resultsNames(dds)  "Intercept" "x_2_vs_1" "condition_B_vs_A" "x2.conditionB" res1 <- lfcShrink(dds, coef=4, type="apeglm") res2 <- lfcShrink(dds, coef=4, type="ashr")