I generated a volcano plot using DESeq2 for a single-cell study transformed into pseudobulk. I am applying log fold change shrinkage using the apeglm method.

However, the resulting plot looks unusual. It does not resemble a typical volcano plot, and many genes have an LFC of 0, yet show varying adjusted p-values (padj).

Are there specific parameters I should adjust when analyzing pseudobulk transformed counts from single-cell RNA-seq?

There is nothing unusual here. There is simply no evidence for differential expression. Almost all genes are shrunken towards zero, due to the lack of evidence.

Check data by PCA if unwanted variation/ batch effects are present.