Short answer. A skipping eBike chain is usually a worn chain, a worn cassette, a bent derailleur hanger, or a shift cable that has stretched. Check chain wear first with a chain checker tool. A stretched chain quickly wears the cassette.
Step by step
Check chain wear. A chain checker tool costs $10 and drops in between links. Past 0.75 percent stretch, replace the chain. Past 1 percent, replace chain and cassette together.
Inspect the cassette. Look for shark tooth shaped wear on the cogs, especially the ones you use most. Worn cassette plus new chain equals continued skipping.
Check the derailleur hanger. Look at the derailleur from behind. It should be parallel to the cassette. Any tilt means a bent hanger, which is a $30 fix if you have the right one.
Adjust the shift cable. A quarter turn of the barrel adjuster on the derailleur fixes most single gear skips. Turn counterclockwise to move the chain toward the wheel.