Rear derailleur keeps skipping under load — anyone dealt with this?

Got about 800 miles on my Rad Power RadRunner Plus and the rear derailleur has started skipping pretty badly when I am pedaling hard or climbing. It is worst in the middle gears. I have already adjusted the barrel adjuster, checked cable tension, and inspected the hanger. I am wondering if the chain is just worn out at 800 miles or if there is something specific about eBike drivetrains that wears faster. Any mechanics or experienced riders here who have dealt with this?