RNAseq biological replicates not clustering in PCA plots
PC1 is 81% of the variance?
This PCA plot confirms that different tissues are different.  You probably already knew that.  I'd make more PCA plots that are tissue specific.  That will be more informative than these.
Personally, I'd also not do DESeq on all of these samples together, unless the goal of your experiment really is to learn the differences between these two tissues.