My maximum range on my 16 month old Model Y is down 10% from when I first purchased it. I don't know if that's "normal" but it sure feels like I got scammed, that's for sure.
But, like all batteries they degrade fastest at the beginning. Not sure how typical your situation is. How many miles?
Pretty sure this is the nature of current lithium battery tech, according to many Tesla owner reports. From what I have gathered, the loss rate will slow and gradually level out above 70% for much of the ten year battery warranty, as long as you follow Tesla’s guidance on battery health.