That’s a good question because the clone army based on Jango Fett shows that cloning tech is basically perfected in this universe. But the conditions were less than perfect in Palpatine’s case. Jango Fett was there in the facility, young and healthy and giving fresh blood samples daily. Palpatine died unexpectedly, was already old, and they might have had to clone him from whatever they could find, like the smell of his farts on his throne cushion or whatever. Cloning is copying so source fidelity matters.
Once I was moving house and we set an old couch out on the sidewalk. It was very large and heavy so we were concerned that no one would take it. But we lived in a poorer area where most everything got taken, and sure enough it did disappear.
A few more days went by and we continued packing to move. The big day finally arrived and I went out that morning to greet the mover truck and found that whoever took the couch had come back and returned it during the night! I was like “you can’t do that!” LOL